test_dataarray.py

from __future__ import absolute_import, division, print_function

import pickle
import warnings
from copy import deepcopy
from textwrap import dedent

import numpy as np
import pandas as pd
import pytest

import xarray as xr
from xarray import (
    DataArray, Dataset, IndexVariable, Variable, align, broadcast)
from xarray.coding.times import CFDatetimeCoder, _import_cftime
from xarray.convert import from_cdms2
from xarray.core import dtypes
from xarray.core.common import ALL_DIMS, full_like
from xarray.core.pycompat import OrderedDict, iteritems
from xarray.tests import (
    LooseVersion, ReturnItem, assert_allclose, assert_array_equal,
    assert_equal, assert_identical, raises_regex, requires_bottleneck,
    requires_cftime, requires_dask, requires_iris, requires_np113,
    requires_scipy, source_ndarray)


class TestDataArray(object):
    @pytest.fixture(autouse=True)
    def setup(self):
        self.attrs = {'attr1': 'value1', 'attr2': 2929}
        self.x = np.random.random((10, 20))
        self.v = Variable(['x', 'y'], self.x)
        self.va = Variable(['x', 'y'], self.x, self.attrs)
        self.ds = Dataset({'foo': self.v})
        self.dv = self.ds['foo']

        self.mindex = pd.MultiIndex.from_product([['a', 'b'], [1, 2]],
                                                 names=('level_1', 'level_2'))
        self.mda = DataArray([0, 1, 2, 3], coords={'x': self.mindex}, dims='x')

    def test_repr(self):
        v = Variable(['time', 'x'], [[1, 2, 3], [4, 5, 6]], {'foo': 'bar'})
        coords = OrderedDict([('x', np.arange(3, dtype=np.int64)),
                              ('other', np.int64(0))])
        data_array = DataArray(v, coords, name='my_variable')
        expected = dedent("""\
        <xarray.DataArray 'my_variable' (time: 2, x: 3)>
        array([[1, 2, 3],
               [4, 5, 6]])
        Coordinates:
          * x        (x) int64 0 1 2
            other    int64 0
        Dimensions without coordinates: time
        Attributes:
            foo:      bar""")
        assert expected == repr(data_array)

    def test_repr_multiindex(self):
        expected = dedent("""\
        <xarray.DataArray (x: 4)>
        array([0, 1, 2, 3])
        Coordinates:
          * x        (x) MultiIndex
          - level_1  (x) object 'a' 'a' 'b' 'b'
          - level_2  (x) int64 1 2 1 2""")
        assert expected == repr(self.mda)

    def test_properties(self):
        assert_equal(self.dv.variable, self.v)
        assert_array_equal(self.dv.values, self.v.values)
        for attr in ['dims', 'dtype', 'shape', 'size', 'nbytes',
                     'ndim', 'attrs']:
            assert getattr(self.dv, attr) == getattr(self.v, attr)
        assert len(self.dv) == len(self.v)
        assert_equal(self.dv.variable, self.v)
        assert set(self.dv.coords) == set(self.ds.coords)
        for k, v in iteritems(self.dv.coords):
            assert_array_equal(v, self.ds.coords[k])
        with pytest.raises(AttributeError):
            self.dv.dataset
        assert isinstance(self.ds['x'].to_index(), pd.Index)
        with raises_regex(ValueError, 'must be 1-dimensional'):
            self.ds['foo'].to_index()
        with pytest.raises(AttributeError):
            self.dv.variable = self.v

    def test_data_property(self):
        array = DataArray(np.zeros((3, 4)))
        actual = array.copy()
        actual.values = np.ones((3, 4))
        assert_array_equal(np.ones((3, 4)), actual.values)
        actual.data = 2 * np.ones((3, 4))
        assert_array_equal(2 * np.ones((3, 4)), actual.data)
        assert_array_equal(actual.data, actual.values)

    def test_indexes(self):
        array = DataArray(np.zeros((2, 3)),
                          [('x', [0, 1]), ('y', ['a', 'b', 'c'])])
        expected = OrderedDict([('x', pd.Index([0, 1])),
                                ('y', pd.Index(['a', 'b', 'c']))])
        assert array.indexes.keys() == expected.keys()
        for k in expected:
            assert array.indexes[k].equals(expected[k])

    def test_get_index(self):
        array = DataArray(np.zeros((2, 3)), coords={'x': ['a', 'b']},
                          dims=['x', 'y'])
        assert array.get_index('x').equals(pd.Index(['a', 'b']))
        assert array.get_index('y').equals(pd.Index([0, 1, 2]))
        with pytest.raises(KeyError):
            array.get_index('z')

    def test_get_index_size_zero(self):
        array = DataArray(np.zeros((0,)), dims=['x'])
        actual = array.get_index('x')
        expected = pd.Index([], dtype=np.int64)
        assert actual.equals(expected)
        assert actual.dtype == expected.dtype

    def test_struct_array_dims(self):
        """
        This test checks subraction of two DataArrays for the case
        when dimension is a structured array.
        """
        # GH837, GH861
        # checking array subraction when dims are the same
        p_data = np.array([('John', 180), ('Stacy', 150), ('Dick', 200)],
                          dtype=[('name', '|S256'), ('height', object)])

        p_data_1 = np.array([('John', 180), ('Stacy', 150), ('Dick', 200)],
                            dtype=[('name', '|S256'), ('height', object)])

        p_data_2 = np.array([('John', 180), ('Dick', 200)],
                            dtype=[('name', '|S256'), ('height', object)])

        weights_0 = DataArray([80, 56, 120], dims=['participant'],
                              coords={'participant': p_data})

        weights_1 = DataArray([81, 52, 115], dims=['participant'],
                              coords={'participant': p_data_1})

        actual = weights_1 - weights_0

        expected = DataArray([1, -4, -5], dims=['participant'],
                             coords={'participant': p_data})

        assert_identical(actual, expected)

        # checking array subraction when dims are not the same
        p_data_1 = np.array([('John', 180), ('Stacy', 151), ('Dick', 200)],
                            dtype=[('name', '|S256'), ('height', object)])

        weights_1 = DataArray([81, 52, 115], dims=['participant'],
                              coords={'participant': p_data_1})

        actual = weights_1 - weights_0

        expected = DataArray([1, -5], dims=['participant'],
                             coords={'participant': p_data_2})

        assert_identical(actual, expected)

        # checking array subraction when dims are not the same and one
        # is np.nan
        p_data_1 = np.array([('John', 180), ('Stacy', np.nan), ('Dick', 200)],
                            dtype=[('name', '|S256'), ('height', object)])

        weights_1 = DataArray([81, 52, 115], dims=['participant'],
                              coords={'participant': p_data_1})

        actual = weights_1 - weights_0

        expected = DataArray([1, -5], dims=['participant'],
                             coords={'participant': p_data_2})

        assert_identical(actual, expected)

    def test_name(self):
        arr = self.dv
        assert arr.name == 'foo'

        copied = arr.copy()
        arr.name = 'bar'
        assert arr.name == 'bar'
        assert_equal(copied, arr)

        actual = DataArray(IndexVariable('x', [3]))
        actual.name = 'y'
        expected = DataArray([3], [('x', [3])], name='y')
        assert_identical(actual, expected)

    def test_dims(self):
        arr = self.dv
        assert arr.dims == ('x', 'y')

        with raises_regex(AttributeError, 'you cannot assign'):
            arr.dims = ('w', 'z')

    def test_sizes(self):
        array = DataArray(np.zeros((3, 4)), dims=['x', 'y'])
        assert array.sizes == {'x': 3, 'y': 4}
        assert tuple(array.sizes) == array.dims
        with pytest.raises(TypeError):
            array.sizes['foo'] = 5

    def test_encoding(self):
        expected = {'foo': 'bar'}
        self.dv.encoding['foo'] = 'bar'
        assert expected == self.dv.encoding

        expected = {'baz': 0}
        self.dv.encoding = expected

        assert expected is not self.dv.encoding

    def test_constructor(self):
        data = np.random.random((2, 3))

        actual = DataArray(data)
        expected = Dataset({None: (['dim_0', 'dim_1'], data)})[None]
        assert_identical(expected, actual)

        actual = DataArray(data, [['a', 'b'], [-1, -2, -3]])
        expected = Dataset({None: (['dim_0', 'dim_1'], data),
                            'dim_0': ('dim_0', ['a', 'b']),
                            'dim_1': ('dim_1', [-1, -2, -3])})[None]
        assert_identical(expected, actual)

        actual = DataArray(data, [pd.Index(['a', 'b'], name='x'),
                                  pd.Index([-1, -2, -3], name='y')])
        expected = Dataset({None: (['x', 'y'], data),
                            'x': ('x', ['a', 'b']),
                            'y': ('y', [-1, -2, -3])})[None]
        assert_identical(expected, actual)

        coords = [['a', 'b'], [-1, -2, -3]]
        actual = DataArray(data, coords, ['x', 'y'])
        assert_identical(expected, actual)

        coords = [pd.Index(['a', 'b'], name='A'),
                  pd.Index([-1, -2, -3], name='B')]
        actual = DataArray(data, coords, ['x', 'y'])
        assert_identical(expected, actual)

        coords = {'x': ['a', 'b'], 'y': [-1, -2, -3]}
        actual = DataArray(data, coords, ['x', 'y'])
        assert_identical(expected, actual)

        coords = [('x', ['a', 'b']), ('y', [-1, -2, -3])]
        actual = DataArray(data, coords)
        assert_identical(expected, actual)

        expected = Dataset({None: (['x', 'y'], data),
                            'x': ('x', ['a', 'b'])})[None]
        actual = DataArray(data, {'x': ['a', 'b']}, ['x', 'y'])
        assert_identical(expected, actual)

        actual = DataArray(data, dims=['x', 'y'])
        expected = Dataset({None: (['x', 'y'], data)})[None]
        assert_identical(expected, actual)

        actual = DataArray(data, dims=['x', 'y'], name='foo')
        expected = Dataset({'foo': (['x', 'y'], data)})['foo']
        assert_identical(expected, actual)

        actual = DataArray(data, name='foo')
        expected = Dataset({'foo': (['dim_0', 'dim_1'], data)})['foo']
        assert_identical(expected, actual)

        actual = DataArray(data, dims=['x', 'y'], attrs={'bar': 2})
        expected = Dataset({None: (['x', 'y'], data, {'bar': 2})})[None]
        assert_identical(expected, actual)

        actual = DataArray(data, dims=['x', 'y'], encoding={'bar': 2})
        expected = Dataset({None: (['x', 'y'], data, {}, {'bar': 2})})[None]
        assert_identical(expected, actual)

    def test_constructor_invalid(self):
        data = np.random.randn(3, 2)

        with raises_regex(ValueError, 'coords is not dict-like'):
            DataArray(data, [[0, 1, 2]], ['x', 'y'])

        with raises_regex(ValueError, 'not a subset of the .* dim'):
            DataArray(data, {'x': [0, 1, 2]}, ['a', 'b'])
        with raises_regex(ValueError, 'not a subset of the .* dim'):
            DataArray(data, {'x': [0, 1, 2]})

        with raises_regex(TypeError, 'is not a string'):
            DataArray(data, dims=['x', None])

        with raises_regex(ValueError, 'conflicting sizes for dim'):
            DataArray([1, 2, 3], coords=[('x', [0, 1])])
        with raises_regex(ValueError, 'conflicting sizes for dim'):
            DataArray([1, 2], coords={'x': [0, 1], 'y': ('x', [1])}, dims='x')

        with raises_regex(ValueError, 'conflicting MultiIndex'):
            DataArray(np.random.rand(4, 4),
                      [('x', self.mindex), ('y', self.mindex)])
        with raises_regex(ValueError, 'conflicting MultiIndex'):
            DataArray(np.random.rand(4, 4),
                      [('x', self.mindex), ('level_1', range(4))])

        with raises_regex(ValueError, 'matching the dimension size'):
            DataArray(data, coords={'x': 0}, dims=['x', 'y'])

    def test_constructor_from_self_described(self):
        data = [[-0.1, 21], [0, 2]]
        expected = DataArray(data,
                             coords={'x': ['a', 'b'], 'y': [-1, -2]},
                             dims=['x', 'y'], name='foobar',
                             attrs={'bar': 2}, encoding={'foo': 3})
        actual = DataArray(expected)
        assert_identical(expected, actual)

        actual = DataArray(expected.values, actual.coords)
        assert_equal(expected, actual)

        frame = pd.DataFrame(data, index=pd.Index(['a', 'b'], name='x'),
                             columns=pd.Index([-1, -2], name='y'))
        actual = DataArray(frame)
        assert_equal(expected, actual)

        series = pd.Series(data[0], index=pd.Index([-1, -2], name='y'))
        actual = DataArray(series)
        assert_equal(expected[0].reset_coords('x', drop=True), actual)

        if hasattr(pd, 'Panel'):
            with warnings.catch_warnings():
                warnings.filterwarnings('ignore', r'\W*Panel is deprecated')
                panel = pd.Panel({0: frame})
            actual = DataArray(panel)
            expected = DataArray([data], expected.coords, ['dim_0', 'x', 'y'])
            expected['dim_0'] = [0]
            assert_identical(expected, actual)

        expected = DataArray(data,
                             coords={'x': ['a', 'b'], 'y': [-1, -2],
                                     'a': 0, 'z': ('x', [-0.5, 0.5])},
                             dims=['x', 'y'])
        actual = DataArray(expected)
        assert_identical(expected, actual)

        actual = DataArray(expected.values, expected.coords)
        assert_identical(expected, actual)

        expected = Dataset({'foo': ('foo', ['a', 'b'])})['foo']
        actual = DataArray(pd.Index(['a', 'b'], name='foo'))
        assert_identical(expected, actual)

        actual = DataArray(IndexVariable('foo', ['a', 'b']))
        assert_identical(expected, actual)

    def test_constructor_from_0d(self):
        expected = Dataset({None: ([], 0)})[None]
        actual = DataArray(0)
        assert_identical(expected, actual)

    @requires_dask
    def test_constructor_dask_coords(self):
        # regression test for GH1684
        import dask.array as da

        coord = da.arange(8, chunks=(4,))
        data = da.random.random((8, 8), chunks=(4, 4)) + 1
        actual = DataArray(data, coords={'x': coord, 'y': coord},
                           dims=['x', 'y'])

        ecoord = np.arange(8)
        expected = DataArray(data, coords={'x': ecoord, 'y': ecoord},
                             dims=['x', 'y'])
        assert_equal(actual, expected)

    def test_equals_and_identical(self):
        orig = DataArray(np.arange(5.0), {'a': 42}, dims='x')

        expected = orig
        actual = orig.copy()
        assert expected.equals(actual)
        assert expected.identical(actual)

        actual = expected.rename('baz')
        assert expected.equals(actual)
        assert not expected.identical(actual)

        actual = expected.rename({'x': 'xxx'})
        assert not expected.equals(actual)
        assert not expected.identical(actual)

        actual = expected.copy()
        actual.attrs['foo'] = 'bar'
        assert expected.equals(actual)
        assert not expected.identical(actual)

        actual = expected.copy()
        actual['x'] = ('x', -np.arange(5))
        assert not expected.equals(actual)
        assert not expected.identical(actual)

        actual = expected.reset_coords(drop=True)
        assert not expected.equals(actual)
        assert not expected.identical(actual)

        actual = orig.copy()
        actual[0] = np.nan
        expected = actual.copy()
        assert expected.equals(actual)
        assert expected.identical(actual)

        actual[:] = np.nan
        assert not expected.equals(actual)
        assert not expected.identical(actual)

        actual = expected.copy()
        actual['a'] = 100000
        assert not expected.equals(actual)
        assert not expected.identical(actual)

    def test_equals_failures(self):
        orig = DataArray(np.arange(5.0), {'a': 42}, dims='x')
        assert not orig.equals(np.arange(5))
        assert not orig.identical(123)
        assert not orig.broadcast_equals({1: 2})

    def test_broadcast_equals(self):
        a = DataArray([0, 0], {'y': 0}, dims='x')
        b = DataArray([0, 0], {'y': ('x', [0, 0])}, dims='x')
        assert a.broadcast_equals(b)
        assert b.broadcast_equals(a)
        assert not a.equals(b)
        assert not a.identical(b)

        c = DataArray([0], coords={'x': 0}, dims='y')
        assert not a.broadcast_equals(c)
        assert not c.broadcast_equals(a)

    def test_getitem(self):
        # strings pull out dataarrays
        assert_identical(self.dv, self.ds['foo'])
        x = self.dv['x']
        y = self.dv['y']
        assert_identical(self.ds['x'], x)
        assert_identical(self.ds['y'], y)

        I = ReturnItem()  # noqa
        for i in [I[:], I[...], I[x.values], I[x.variable], I[x], I[x, y],
                  I[x.values > -1], I[x.variable > -1], I[x > -1],
                  I[x > -1, y > -1]]:
            assert_equal(self.dv, self.dv[i])
        for i in [I[0], I[:, 0], I[:3, :2],
                  I[x.values[:3]], I[x.variable[:3]],
                  I[x[:3]], I[x[:3], y[:4]],
                  I[x.values > 3], I[x.variable > 3],
                  I[x > 3], I[x > 3, y > 3]]:
            assert_array_equal(self.v[i], self.dv[i])

    def test_getitem_dict(self):
        actual = self.dv[{'x': slice(3), 'y': 0}]
        expected = self.dv.isel(x=slice(3), y=0)
        assert_identical(expected, actual)

    def test_getitem_coords(self):
        orig = DataArray([[10], [20]],
                         {'x': [1, 2], 'y': [3], 'z': 4,
                          'x2': ('x', ['a', 'b']),
                          'y2': ('y', ['c']),
                          'xy': (['y', 'x'], [['d', 'e']])},
                         dims=['x', 'y'])

        assert_identical(orig, orig[:])
        assert_identical(orig, orig[:, :])
        assert_identical(orig, orig[...])
        assert_identical(orig, orig[:2, :1])
        assert_identical(orig, orig[[0, 1], [0]])

        actual = orig[0, 0]
        expected = DataArray(
            10, {'x': 1, 'y': 3, 'z': 4, 'x2': 'a', 'y2': 'c', 'xy': 'd'})
        assert_identical(expected, actual)

        actual = orig[0, :]
        expected = DataArray(
            [10], {'x': 1, 'y': [3], 'z': 4, 'x2': 'a', 'y2': ('y', ['c']),
                   'xy': ('y', ['d'])},
            dims='y')
        assert_identical(expected, actual)

        actual = orig[:, 0]
        expected = DataArray(
            [10, 20], {'x': [1, 2], 'y': 3, 'z': 4, 'x2': ('x', ['a', 'b']),
                       'y2': 'c', 'xy': ('x', ['d', 'e'])},
            dims='x')
        assert_identical(expected, actual)

    def test_getitem_dataarray(self):
        # It should not conflict
        da = DataArray(np.arange(12).reshape((3, 4)), dims=['x', 'y'])
        ind = DataArray([[0, 1], [0, 1]], dims=['x', 'z'])
        actual = da[ind]
        assert_array_equal(actual, da.values[[[0, 1], [0, 1]], :])

        da = DataArray(np.arange(12).reshape((3, 4)), dims=['x', 'y'],
                       coords={'x': [0, 1, 2], 'y': ['a', 'b', 'c', 'd']})
        ind = xr.DataArray([[0, 1], [0, 1]], dims=['X', 'Y'])
        actual = da[ind]
        expected = da.values[[[0, 1], [0, 1]], :]
        assert_array_equal(actual, expected)
        assert actual.dims == ('X', 'Y', 'y')

        # boolean indexing
        ind = xr.DataArray([True, True, False], dims=['x'])
        assert_equal(da[ind], da[[0, 1], :])
        assert_equal(da[ind], da[[0, 1]])
        assert_equal(da[ind], da[ind.values])

    def test_setitem(self):
        # basic indexing should work as numpy's indexing
        tuples = [(0, 0), (0, slice(None, None)),
                  (slice(None, None), slice(None, None)),
                  (slice(None, None), 0),
                  ([1, 0], slice(None, None)),
                  (slice(None, None), [1, 0])]
        for t in tuples:
            expected = np.arange(6).reshape(3, 2)
            orig = DataArray(np.arange(6).reshape(3, 2),
                             {'x': [1, 2, 3], 'y': ['a', 'b'], 'z': 4,
                              'x2': ('x', ['a', 'b', 'c']),
                              'y2': ('y', ['d', 'e'])},
                             dims=['x', 'y'])
            orig[t] = 1
            expected[t] = 1
            assert_array_equal(orig.values, expected)

    def test_setitem_fancy(self):
        # vectorized indexing
        da = DataArray(np.ones((3, 2)), dims=['x', 'y'])
        ind = Variable(['a'], [0, 1])
        da[dict(x=ind, y=ind)] = 0
        expected = DataArray([[0, 1], [1, 0], [1, 1]], dims=['x', 'y'])
        assert_identical(expected, da)
        # assign another 0d-variable
        da[dict(x=ind, y=ind)] = Variable((), 0)
        expected = DataArray([[0, 1], [1, 0], [1, 1]], dims=['x', 'y'])
        assert_identical(expected, da)
        # assign another 1d-variable
        da[dict(x=ind, y=ind)] = Variable(['a'], [2, 3])
        expected = DataArray([[2, 1], [1, 3], [1, 1]], dims=['x', 'y'])
        assert_identical(expected, da)

        # 2d-vectorized indexing
        da = DataArray(np.ones((3, 2)), dims=['x', 'y'])
        ind_x = DataArray([[0, 1]], dims=['a', 'b'])
        ind_y = DataArray([[1, 0]], dims=['a', 'b'])
        da[dict(x=ind_x, y=ind_y)] = 0
        expected = DataArray([[1, 0], [0, 1], [1, 1]], dims=['x', 'y'])
        assert_identical(expected, da)

        da = DataArray(np.ones((3, 2)), dims=['x', 'y'])
        ind = Variable(['a'], [0, 1])
        da[ind] = 0
        expected = DataArray([[0, 0], [0, 0], [1, 1]], dims=['x', 'y'])
        assert_identical(expected, da)

    def test_setitem_dataarray(self):
        def get_data():
            return DataArray(np.ones((4, 3, 2)), dims=['x', 'y', 'z'],
                             coords={'x': np.arange(4), 'y': ['a', 'b', 'c'],
                                     'non-dim': ('x', [1, 3, 4, 2])})

        da = get_data()
        # indexer with inconsistent coordinates.
        ind = DataArray(np.arange(1, 4), dims=['x'],
                        coords={'x': np.random.randn(3)})
        with raises_regex(IndexError, "dimension coordinate 'x'"):
            da[dict(x=ind)] = 0

        # indexer with consistent coordinates.
        ind = DataArray(np.arange(1, 4), dims=['x'],
                        coords={'x': np.arange(1, 4)})
        da[dict(x=ind)] = 0  # should not raise
        assert np.allclose(da[dict(x=ind)].values, 0)
        assert_identical(da['x'], get_data()['x'])
        assert_identical(da['non-dim'], get_data()['non-dim'])

        da = get_data()
        # conflict in the assigning values
        value = xr.DataArray(np.zeros((3, 3, 2)), dims=['x', 'y', 'z'],
                             coords={'x': [0, 1, 2],
                                     'non-dim': ('x', [0, 2, 4])})
        with raises_regex(IndexError, "dimension coordinate 'x'"):
            da[dict(x=ind)] = value

        # consistent coordinate in the assigning values
        value = xr.DataArray(np.zeros((3, 3, 2)), dims=['x', 'y', 'z'],
                             coords={'x': [1, 2, 3],
                                     'non-dim': ('x', [0, 2, 4])})
        da[dict(x=ind)] = value
        assert np.allclose(da[dict(x=ind)].values, 0)
        assert_identical(da['x'], get_data()['x'])
        assert_identical(da['non-dim'], get_data()['non-dim'])

        # Conflict in the non-dimension coordinate
        value = xr.DataArray(np.zeros((3, 3, 2)), dims=['x', 'y', 'z'],
                             coords={'x': [1, 2, 3],
                                     'non-dim': ('x', [0, 2, 4])})
        da[dict(x=ind)] = value  # should not raise

        # conflict in the assigning values
        value = xr.DataArray(np.zeros((3, 3, 2)), dims=['x', 'y', 'z'],
                             coords={'x': [0, 1, 2],
                                     'non-dim': ('x', [0, 2, 4])})
        with raises_regex(IndexError, "dimension coordinate 'x'"):
            da[dict(x=ind)] = value

        # consistent coordinate in the assigning values
        value = xr.DataArray(np.zeros((3, 3, 2)), dims=['x', 'y', 'z'],
                             coords={'x': [1, 2, 3],
                                     'non-dim': ('x', [0, 2, 4])})
        da[dict(x=ind)] = value  # should not raise

    def test_contains(self):
        data_array = DataArray([1, 2])
        assert 1 in data_array
        assert 3 not in data_array

    def test_attr_sources_multiindex(self):
        # make sure attr-style access for multi-index levels
        # returns DataArray objects
        assert isinstance(self.mda.level_1, DataArray)

    def test_pickle(self):
        data = DataArray(np.random.random((3, 3)), dims=('id', 'time'))
        roundtripped = pickle.loads(pickle.dumps(data))
        assert_identical(data, roundtripped)

    @requires_dask
    def test_chunk(self):
        unblocked = DataArray(np.ones((3, 4)))
        assert unblocked.chunks is None

        blocked = unblocked.chunk()
        assert blocked.chunks == ((3,), (4,))

        blocked = unblocked.chunk(chunks=((2, 1), (2, 2)))
        assert blocked.chunks == ((2, 1), (2, 2))

        blocked = unblocked.chunk(chunks=(3, 3))
        assert blocked.chunks == ((3,), (3, 1))

        assert blocked.load().chunks is None

        # Check that kwargs are passed
        import dask.array as da
        blocked = unblocked.chunk(name_prefix='testname_')
        assert isinstance(blocked.data, da.Array)
        assert 'testname_' in blocked.data.name

    def test_isel(self):
        assert_identical(self.dv[0], self.dv.isel(x=0))
        assert_identical(self.dv, self.dv.isel(x=slice(None)))
        assert_identical(self.dv[:3], self.dv.isel(x=slice(3)))
        assert_identical(self.dv[:3, :5], self.dv.isel(x=slice(3), y=slice(5)))

    def test_isel_types(self):
        # regression test for #1405
        da = DataArray([1, 2, 3], dims='x')
        # uint64
        assert_identical(da.isel(x=np.array([0], dtype="uint64")),
                         da.isel(x=np.array([0])))
        # uint32
        assert_identical(da.isel(x=np.array([0], dtype="uint32")),
                         da.isel(x=np.array([0])))
        # int64
        assert_identical(da.isel(x=np.array([0], dtype="int64")),
                         da.isel(x=np.array([0])))

    @pytest.mark.filterwarnings('ignore::DeprecationWarning')
    def test_isel_fancy(self):
        shape = (10, 7, 6)
        np_array = np.random.random(shape)
        da = DataArray(np_array, dims=['time', 'y', 'x'],
                       coords={'time': np.arange(0, 100, 10)})
        y = [1, 3]
        x = [3, 0]

        expected = da.values[:, y, x]

        actual = da.isel(y=(('test_coord', ), y), x=(('test_coord', ), x))
        assert actual.coords['test_coord'].shape == (len(y), )
        assert list(actual.coords) == ['time']
        assert actual.dims == ('time', 'test_coord')

        np.testing.assert_equal(actual, expected)

        # a few corner cases
        da.isel(time=(('points',), [1, 2]), x=(('points',), [2, 2]),
                y=(('points',), [3, 4]))
        np.testing.assert_allclose(
            da.isel_points(time=[1], x=[2], y=[4]).values.squeeze(),
            np_array[1, 4, 2].squeeze())
        da.isel(time=(('points', ), [1, 2]))
        y = [-1, 0]
        x = [-2, 2]
        expected = da.values[:, y, x]
        actual = da.isel(x=(('points', ), x), y=(('points', ), y)).values
        np.testing.assert_equal(actual, expected)

        # test that the order of the indexers doesn't matter
        assert_identical(
            da.isel(y=(('points', ), y), x=(('points', ), x)),
            da.isel(x=(('points', ), x), y=(('points', ), y)))

        # make sure we're raising errors in the right places
        with raises_regex(IndexError,
                          'Dimensions of indexers mismatch'):
            da.isel(y=(('points', ), [1, 2]), x=(('points', ), [1, 2, 3]))

        # tests using index or DataArray as indexers
        stations = Dataset()
        stations['station'] = (('station', ), ['A', 'B', 'C'])
        stations['dim1s'] = (('station', ), [1, 2, 3])
        stations['dim2s'] = (('station', ), [4, 5, 1])

        actual = da.isel(x=stations['dim1s'], y=stations['dim2s'])
        assert 'station' in actual.coords
        assert 'station' in actual.dims
        assert_identical(actual['station'], stations['station'])

        with raises_regex(ValueError, 'conflicting values for '):
            da.isel(x=DataArray([0, 1, 2], dims='station',
                                coords={'station': [0, 1, 2]}),
                    y=DataArray([0, 1, 2], dims='station',
                                coords={'station': [0, 1, 3]}))

        # multi-dimensional selection
        stations = Dataset()
        stations['a'] = (('a', ), ['A', 'B', 'C'])
        stations['b'] = (('b', ), [0, 1])
        stations['dim1s'] = (('a', 'b'), [[1, 2], [2, 3], [3, 4]])
        stations['dim2s'] = (('a', ), [4, 5, 1])

        actual = da.isel(x=stations['dim1s'], y=stations['dim2s'])
        assert 'a' in actual.coords
        assert 'a' in actual.dims
        assert 'b' in actual.coords
        assert 'b' in actual.dims
        assert_identical(actual['a'], stations['a'])
        assert_identical(actual['b'], stations['b'])
        expected = da.variable[:, stations['dim2s'].variable,
                               stations['dim1s'].variable]
        assert_array_equal(actual, expected)

    def test_sel(self):
        self.ds['x'] = ('x', np.array(list('abcdefghij')))
        da = self.ds['foo']
        assert_identical(da, da.sel(x=slice(None)))
        assert_identical(da[1], da.sel(x='b'))
        assert_identical(da[:3], da.sel(x=slice('c')))
        assert_identical(da[:3], da.sel(x=['a', 'b', 'c']))
        assert_identical(da[:, :4], da.sel(y=(self.ds['y'] < 4)))
        # verify that indexing with a dataarray works
        b = DataArray('b')
        assert_identical(da[1], da.sel(x=b))
        assert_identical(da[[1]], da.sel(x=slice(b, b)))

    def test_sel_dataarray(self):
        # indexing with DataArray
        self.ds['x'] = ('x', np.array(list('abcdefghij')))
        da = self.ds['foo']

        ind = DataArray(['a', 'b', 'c'], dims=['x'])
        actual = da.sel(x=ind)
        assert_identical(actual, da.isel(x=[0, 1, 2]))

        # along new dimension
        ind = DataArray(['a', 'b', 'c'], dims=['new_dim'])
        actual = da.sel(x=ind)
        assert_array_equal(actual, da.isel(x=[0, 1, 2]))
        assert 'new_dim' in actual.dims

        # with coordinate
        ind = DataArray(['a', 'b', 'c'], dims=['new_dim'],
                        coords={'new_dim': [0, 1, 2]})
        actual = da.sel(x=ind)
        assert_array_equal(actual, da.isel(x=[0, 1, 2]))
        assert 'new_dim' in actual.dims
        assert 'new_dim' in actual.coords
        assert_equal(actual['new_dim'].drop('x'), ind['new_dim'])

    def test_sel_invalid_slice(self):
        array = DataArray(np.arange(10), [('x', np.arange(10))])
        with raises_regex(ValueError, 'cannot use non-scalar arrays'):
            array.sel(x=slice(array.x))

    def test_sel_dataarray_datetime(self):
        # regression test for GH1240
        times = pd.date_range('2000-01-01', freq='D', periods=365)
        array = DataArray(np.arange(365), [('time', times)])
        result = array.sel(time=slice(array.time[0], array.time[-1]))
        assert_equal(result, array)

        array = DataArray(np.arange(365), [('delta', times - times[0])])
        result = array.sel(delta=slice(array.delta[0], array.delta[-1]))
        assert_equal(result, array)

    def test_sel_no_index(self):
        array = DataArray(np.arange(10), dims='x')
        assert_identical(array[0], array.sel(x=0))
        assert_identical(array[:5], array.sel(x=slice(5)))
        assert_identical(array[[0, -1]], array.sel(x=[0, -1]))
        assert_identical(
            array[array < 5], array.sel(x=(array < 5)))

    def test_sel_method(self):
        data = DataArray(np.random.randn(3, 4),
                         [('x', [0, 1, 2]), ('y', list('abcd'))])

        expected = data.sel(y=['a', 'b'])
        actual = data.sel(y=['ab', 'ba'], method='pad')
        assert_identical(expected, actual)

        expected = data.sel(x=[1, 2])
        actual = data.sel(x=[0.9, 1.9], method='backfill', tolerance=1)
        assert_identical(expected, actual)

    def test_sel_drop(self):
        data = DataArray([1, 2, 3], [('x', [0, 1, 2])])
        expected = DataArray(1)
        selected = data.sel(x=0, drop=True)
        assert_identical(expected, selected)

        expected = DataArray(1, {'x': 0})
        selected = data.sel(x=0, drop=False)
        assert_identical(expected, selected)

        data = DataArray([1, 2, 3], dims=['x'])
        expected = DataArray(1)
        selected = data.sel(x=0, drop=True)
        assert_identical(expected, selected)

    def test_isel_drop(self):
        data = DataArray([1, 2, 3], [('x', [0, 1, 2])])
        expected = DataArray(1)
        selected = data.isel(x=0, drop=True)
        assert_identical(expected, selected)

        expected = DataArray(1, {'x': 0})
        selected = data.isel(x=0, drop=False)
        assert_identical(expected, selected)

    @pytest.mark.filterwarnings("ignore:Dataset.isel_points")
    def test_isel_points(self):
        shape = (10, 5, 6)
        np_array = np.random.random(shape)
        da = DataArray(np_array, dims=['time', 'y', 'x'],
                       coords={'time': np.arange(0, 100, 10)})
        y = [1, 3]
        x = [3, 0]

        expected = da.values[:, y, x]

        actual = da.isel_points(y=y, x=x, dim='test_coord')
        assert actual.coords['test_coord'].shape == (len(y), )
        assert list(actual.coords) == ['time']
        assert actual.dims == ('test_coord', 'time')

        actual = da.isel_points(y=y, x=x)
        assert 'points' in actual.dims
        # Note that because xarray always concatenates along the first
        # dimension, We must transpose the result to match the numpy style of
        # concatenation.
        np.testing.assert_equal(actual.T, expected)

        # a few corner cases
        da.isel_points(time=[1, 2], x=[2, 2], y=[3, 4])
        np.testing.assert_allclose(
            da.isel_points(time=[1], x=[2], y=[4]).values.squeeze(),
            np_array[1, 4, 2].squeeze())
        da.isel_points(time=[1, 2])
        y = [-1, 0]
        x = [-2, 2]
        expected = da.values[:, y, x]
        actual = da.isel_points(x=x, y=y).values
        np.testing.assert_equal(actual.T, expected)

        # test that the order of the indexers doesn't matter
        assert_identical(
            da.isel_points(y=y, x=x),
            da.isel_points(x=x, y=y))

        # make sure we're raising errors in the right places
        with raises_regex(ValueError,
                          'All indexers must be the same length'):
            da.isel_points(y=[1, 2], x=[1, 2, 3])
        with raises_regex(ValueError,
                          'dimension bad_key does not exist'):
            da.isel_points(bad_key=[1, 2])
        with raises_regex(TypeError, 'Indexers must be integers'):
            da.isel_points(y=[1.5, 2.2])
        with raises_regex(TypeError, 'Indexers must be integers'):
            da.isel_points(x=[1, 2, 3], y=slice(3))
        with raises_regex(ValueError,
                          'Indexers must be 1 dimensional'):
            da.isel_points(y=1, x=2)
        with raises_regex(ValueError,
                          'Existing dimension names are not'):
            da.isel_points(y=[1, 2], x=[1, 2], dim='x')

        # using non string dims
        actual = da.isel_points(y=[1, 2], x=[1, 2], dim=['A', 'B'])
        assert 'points' in actual.coords

    def test_loc(self):
        self.ds['x'] = ('x', np.array(list('abcdefghij')))
        da = self.ds['foo']
        assert_identical(da[:3], da.loc[:'c'])
        assert_identical(da[1], da.loc['b'])
        assert_identical(da[1], da.loc[{'x': 'b'}])
        assert_identical(da[1], da.loc['b', ...])
        assert_identical(da[:3], da.loc[['a', 'b', 'c']])
        assert_identical(da[:3, :4], da.loc[['a', 'b', 'c'], np.arange(4)])
        assert_identical(da[:, :4], da.loc[:, self.ds['y'] < 4])

    def test_loc_assign(self):
        self.ds['x'] = ('x', np.array(list('abcdefghij')))
        da = self.ds['foo']
        # assignment
        da.loc['a':'j'] = 0
        assert np.all(da.values == 0)
        da.loc[{'x': slice('a', 'j')}] = 2
        assert np.all(da.values == 2)

        da.loc[{'x': slice('a', 'j')}] = 2
        assert np.all(da.values == 2)

        # Multi dimensional case
        da = DataArray(np.arange(12).reshape(3, 4), dims=['x', 'y'])
        da.loc[0, 0] = 0
        assert da.values[0, 0] == 0
        assert da.values[0, 1] != 0

        da = DataArray(np.arange(12).reshape(3, 4), dims=['x', 'y'])
        da.loc[0] = 0
        assert np.all(da.values[0] == np.zeros(4))
        assert da.values[1, 0] != 0

    def test_loc_assign_dataarray(self):
        def get_data():
            return DataArray(np.ones((4, 3, 2)), dims=['x', 'y', 'z'],
                             coords={'x': np.arange(4), 'y': ['a', 'b', 'c'],
                                     'non-dim': ('x', [1, 3, 4, 2])})

        da = get_data()
        # indexer with inconsistent coordinates.
        ind = DataArray(np.arange(1, 4), dims=['y'],
                        coords={'y': np.random.randn(3)})
        with raises_regex(IndexError, "dimension coordinate 'y'"):
            da.loc[dict(x=ind)] = 0

        # indexer with consistent coordinates.
        ind = DataArray(np.arange(1, 4), dims=['x'],
                        coords={'x': np.arange(1, 4)})
        da.loc[dict(x=ind)] = 0  # should not raise
        assert np.allclose(da[dict(x=ind)].values, 0)
        assert_identical(da['x'], get_data()['x'])
        assert_identical(da['non-dim'], get_data()['non-dim'])

        da = get_data()
        # conflict in the assigning values
        value = xr.DataArray(np.zeros((3, 3, 2)), dims=['x', 'y', 'z'],
                             coords={'x': [0, 1, 2],
                                     'non-dim': ('x', [0, 2, 4])})
        with raises_regex(IndexError, "dimension coordinate 'x'"):
            da.loc[dict(x=ind)] = value

        # consistent coordinate in the assigning values
        value = xr.DataArray(np.zeros((3, 3, 2)), dims=['x', 'y', 'z'],
                             coords={'x': [1, 2, 3],
                                     'non-dim': ('x', [0, 2, 4])})
        da.loc[dict(x=ind)] = value
        assert np.allclose(da[dict(x=ind)].values, 0)
        assert_identical(da['x'], get_data()['x'])
        assert_identical(da['non-dim'], get_data()['non-dim'])

    def test_loc_single_boolean(self):
        data = DataArray([0, 1], coords=[[True, False]])
        assert data.loc[True] == 0
        assert data.loc[False] == 1

    def test_selection_multiindex(self):
        mindex = pd.MultiIndex.from_product([['a', 'b'], [1, 2], [-1, -2]],
                                            names=('one', 'two', 'three'))
        mdata = DataArray(range(8), [('x', mindex)])

        def test_sel(lab_indexer, pos_indexer, replaced_idx=False,
                     renamed_dim=None):
            da = mdata.sel(x=lab_indexer)
            expected_da = mdata.isel(x=pos_indexer)
            if not replaced_idx:
                assert_identical(da, expected_da)
            else:
                if renamed_dim:
                    assert da.dims[0] == renamed_dim
                    da = da.rename({renamed_dim: 'x'})
                assert_identical(da.variable, expected_da.variable)
                assert not da['x'].equals(expected_da['x'])

        test_sel(('a', 1, -1), 0)
        test_sel(('b', 2, -2), -1)
        test_sel(('a', 1), [0, 1], replaced_idx=True, renamed_dim='three')
        test_sel(('a',), range(4), replaced_idx=True)
        test_sel('a', range(4), replaced_idx=True)
        test_sel([('a', 1, -1), ('b', 2, -2)], [0, 7])
        test_sel(slice('a', 'b'), range(8))
        test_sel(slice(('a', 1), ('b', 1)), range(6))
        test_sel({'one': 'a', 'two': 1, 'three': -1}, 0)
        test_sel({'one': 'a', 'two': 1}, [0, 1], replaced_idx=True,
                 renamed_dim='three')
        test_sel({'one': 'a'}, range(4), replaced_idx=True)

        assert_identical(mdata.loc['a'], mdata.sel(x='a'))
        assert_identical(mdata.loc[('a', 1), ...], mdata.sel(x=('a', 1)))
        assert_identical(mdata.loc[{'one': 'a'}, ...],
                         mdata.sel(x={'one': 'a'}))
        with pytest.raises(IndexError):
            mdata.loc[('a', 1)]

        assert_identical(mdata.sel(x={'one': 'a', 'two': 1}),
                         mdata.sel(one='a', two=1))

    def test_selection_multiindex(self):
        # GH2619. For MultiIndex, we need to call remove_unused.
        ds = xr.DataArray(np.arange(40).reshape(8, 5), dims=['x', 'y'],
                          coords={'x': np.arange(8), 'y': np.arange(5)})
        ds = ds.stack(xy=['x', 'y'])
        ds_isel = ds.isel(xy=ds['x'] < 4)
        with pytest.raises(KeyError):
            ds_isel.sel(x=5)

        actual = ds_isel.unstack()
        expected = ds.reset_index('xy').isel(xy=ds['x'] < 4)
        expected = expected.set_index(xy=['x', 'y']).unstack()
        assert_identical(expected, actual)

    def test_virtual_default_coords(self):
        array = DataArray(np.zeros((5,)), dims='x')
        expected = DataArray(range(5), dims='x', name='x')
        assert_identical(expected, array['x'])
        assert_identical(expected, array.coords['x'])

    def test_virtual_time_components(self):
        dates = pd.date_range('2000-01-01', periods=10)
        da = DataArray(np.arange(1, 11), [('time', dates)])

        assert_array_equal(da['time.dayofyear'], da.values)
        assert_array_equal(da.coords['time.dayofyear'], da.values)

    def test_coords(self):
        # use int64 to ensure repr() consistency on windows
        coords = [IndexVariable('x', np.array([-1, -2], 'int64')),
                  IndexVariable('y', np.array([0, 1, 2], 'int64'))]
        da = DataArray(np.random.randn(2, 3), coords, name='foo')

        assert 2 == len(da.coords)

        assert ['x', 'y'] == list(da.coords)

        assert coords[0].identical(da.coords['x'])
        assert coords[1].identical(da.coords['y'])

        assert 'x' in da.coords
        assert 0 not in da.coords
        assert 'foo' not in da.coords

        with pytest.raises(KeyError):
            da.coords[0]
        with pytest.raises(KeyError):
            da.coords['foo']

        expected = dedent("""\
        Coordinates:
          * x        (x) int64 -1 -2
          * y        (y) int64 0 1 2""")
        actual = repr(da.coords)
        assert expected == actual

        del da.coords['x']
        expected = DataArray(da.values, {'y': [0, 1, 2]}, dims=['x', 'y'],
                             name='foo')
        assert_identical(da, expected)

        with raises_regex(ValueError, 'conflicting MultiIndex'):
            self.mda['level_1'] = np.arange(4)
            self.mda.coords['level_1'] = np.arange(4)

    def test_coords_to_index(self):
        da = DataArray(np.zeros((2, 3)), [('x', [1, 2]), ('y', list('abc'))])

        with raises_regex(ValueError, 'no valid index'):
            da[0, 0].coords.to_index()

        expected = pd.Index(['a', 'b', 'c'], name='y')
        actual = da[0].coords.to_index()
        assert expected.equals(actual)

        expected = pd.MultiIndex.from_product([[1, 2], ['a', 'b', 'c']],
                                              names=['x', 'y'])
        actual = da.coords.to_index()
        assert expected.equals(actual)

        expected = pd.MultiIndex.from_product([['a', 'b', 'c'], [1, 2]],
                                              names=['y', 'x'])
        actual = da.coords.to_index(['y', 'x'])
        assert expected.equals(actual)

        with raises_regex(ValueError, 'ordered_dims must match'):
            da.coords.to_index(['x'])

    def test_coord_coords(self):
        orig = DataArray([10, 20],
                         {'x': [1, 2], 'x2': ('x', ['a', 'b']), 'z': 4},
                         dims='x')

        actual = orig.coords['x']
        expected = DataArray([1, 2], {'z': 4, 'x2': ('x', ['a', 'b']),
                                      'x': [1, 2]},
                             dims='x', name='x')
        assert_identical(expected, actual)

        del actual.coords['x2']
        assert_identical(
            expected.reset_coords('x2', drop=True), actual)

        actual.coords['x3'] = ('x', ['a', 'b'])
        expected = DataArray([1, 2], {'z': 4, 'x3': ('x', ['a', 'b']),
                                      'x': [1, 2]},
                             dims='x', name='x')
        assert_identical(expected, actual)

    def test_reset_coords(self):
        data = DataArray(np.zeros((3, 4)),
                         {'bar': ('x', ['a', 'b', 'c']),
                          'baz': ('y', range(4)),
                          'y': range(4)},
                         dims=['x', 'y'],
                         name='foo')

        actual = data.reset_coords()
        expected = Dataset({'foo': (['x', 'y'], np.zeros((3, 4))),
                            'bar': ('x', ['a', 'b', 'c']),
                            'baz': ('y', range(4)),
                            'y': range(4)})
        assert_identical(actual, expected)

        actual = data.reset_coords(['bar', 'baz'])
        assert_identical(actual, expected)

        actual = data.reset_coords('bar')
        expected = Dataset({'foo': (['x', 'y'], np.zeros((3, 4))),
                            'bar': ('x', ['a', 'b', 'c'])},
                           {'baz': ('y', range(4)), 'y': range(4)})
        assert_identical(actual, expected)

        actual = data.reset_coords(['bar'])
        assert_identical(actual, expected)

        actual = data.reset_coords(drop=True)
        expected = DataArray(np.zeros((3, 4)), coords={'y': range(4)},
                             dims=['x', 'y'], name='foo')
        assert_identical(actual, expected)

        actual = data.copy()
        actual = actual.reset_coords(drop=True)
        assert_identical(actual, expected)

        actual = data.reset_coords('bar', drop=True)
        expected = DataArray(np.zeros((3, 4)),
                             {'baz': ('y', range(4)), 'y': range(4)},
                             dims=['x', 'y'], name='foo')
        assert_identical(actual, expected)

        with pytest.warns(FutureWarning, message='The inplace argument'):
            with raises_regex(ValueError, 'cannot reset coord'):
                data = data.reset_coords(inplace=True)
        with raises_regex(ValueError, 'cannot be found'):
            data.reset_coords('foo', drop=True)
        with raises_regex(ValueError, 'cannot be found'):
            data.reset_coords('not_found')
        with raises_regex(ValueError, 'cannot remove index'):
            data.reset_coords('y')

    def test_assign_coords(self):
        array = DataArray(10)
        actual = array.assign_coords(c=42)
        expected = DataArray(10, {'c': 42})
        assert_identical(actual, expected)

        array = DataArray([1, 2, 3, 4], {'c': ('x', [0, 0, 1, 1])}, dims='x')
        actual = array.groupby('c').assign_coords(d=lambda a: a.mean())
        expected = array.copy()
        expected.coords['d'] = ('x', [1.5, 1.5, 3.5, 3.5])
        assert_identical(actual, expected)

        with raises_regex(ValueError, 'conflicting MultiIndex'):
            self.mda.assign_coords(level_1=range(4))

        # GH: 2112
        da = xr.DataArray([0, 1, 2], dims='x')
        with pytest.raises(ValueError):
            da['x'] = [0, 1, 2, 3]  # size conflict
        with pytest.raises(ValueError):
            da.coords['x'] = [0, 1, 2, 3]  # size conflict

    def test_coords_alignment(self):
        lhs = DataArray([1, 2, 3], [('x', [0, 1, 2])])
        rhs = DataArray([2, 3, 4], [('x', [1, 2, 3])])
        lhs.coords['rhs'] = rhs

        expected = DataArray([1, 2, 3],
                             coords={'rhs': ('x', [np.nan, 2, 3]),
                                     'x': [0, 1, 2]},
                             dims='x')
        assert_identical(lhs, expected)

    def test_coords_replacement_alignment(self):
        # regression test for GH725
        arr = DataArray([0, 1, 2], dims=['abc'])
        new_coord = DataArray([1, 2, 3], dims=['abc'], coords=[[1, 2, 3]])
        arr['abc'] = new_coord
        expected = DataArray([0, 1, 2], coords=[('abc', [1, 2, 3])])
        assert_identical(arr, expected)

    def test_coords_non_string(self):
        arr = DataArray(0, coords={1: 2})
        actual = arr.coords[1]
        expected = DataArray(2, coords={1: 2}, name=1)
        assert_identical(actual, expected)

    def test_reindex_like(self):
        foo = DataArray(np.random.randn(5, 6),
                        [('x', range(5)), ('y', range(6))])
        bar = foo[:2, :2]
        assert_identical(foo.reindex_like(bar), bar)

        expected = foo.copy()
        expected[:] = np.nan
        expected[:2, :2] = bar
        assert_identical(bar.reindex_like(foo), expected)

    def test_reindex_like_no_index(self):
        foo = DataArray(np.random.randn(5, 6), dims=['x', 'y'])
        assert_identical(foo, foo.reindex_like(foo))

        bar = foo[:4]
        with raises_regex(
                ValueError, 'different size for unlabeled'):
            foo.reindex_like(bar)

    @pytest.mark.filterwarnings('ignore:Indexer has dimensions')
    def test_reindex_regressions(self):
        # regression test for #279
        expected = DataArray(np.random.randn(5), coords=[("time", range(5))])
        time2 = DataArray(np.arange(5), dims="time2")
        actual = expected.reindex(time=time2)
        assert_identical(actual, expected)

        # regression test for #736, reindex can not change complex nums dtype
        x = np.array([1, 2, 3], dtype=np.complex)
        x = DataArray(x, coords=[[0.1, 0.2, 0.3]])
        y = DataArray([2, 5, 6, 7, 8], coords=[[-1.1, 0.21, 0.31, 0.41, 0.51]])
        re_dtype = x.reindex_like(y, method='pad').dtype
        assert x.dtype == re_dtype

    def test_reindex_method(self):
        x = DataArray([10, 20], dims='y', coords={'y': [0, 1]})
        y = [-0.1, 0.5, 1.1]
        actual = x.reindex(y=y, method='backfill', tolerance=0.2)
        expected = DataArray([10, np.nan, np.nan], coords=[('y', y)])
        assert_identical(expected, actual)

        alt = Dataset({'y': y})
        actual = x.reindex_like(alt, method='backfill')
        expected = DataArray([10, 20, np.nan], coords=[('y', y)])
        assert_identical(expected, actual)

    def test_rename(self):
        renamed = self.dv.rename('bar')
        assert_identical(
            renamed.to_dataset(), self.ds.rename({'foo': 'bar'}))
        assert renamed.name == 'bar'

        renamed = self.dv.x.rename({'x': 'z'}).rename('z')
        assert_identical(
            renamed, self.ds.rename({'x': 'z'}).z)
        assert renamed.name == 'z'
        assert renamed.dims == ('z',)

        renamed_kwargs = self.dv.x.rename(x='z').rename('z')
        assert_identical(renamed, renamed_kwargs)

    def test_swap_dims(self):
        array = DataArray(np.random.randn(3), {'y': ('x', list('abc'))}, 'x')
        expected = DataArray(array.values, {'y': list('abc')}, dims='y')
        actual = array.swap_dims({'x': 'y'})
        assert_identical(expected, actual)

    def test_expand_dims_error(self):
        array = DataArray(np.random.randn(3, 4), dims=['x', 'dim_0'],
                          coords={'x': np.linspace(0.0, 1.0, 3)},
                          attrs={'key': 'entry'})

        with raises_regex(ValueError, 'dim should be str or'):
            array.expand_dims(0)
        with raises_regex(ValueError, 'lengths of dim and axis'):
            # dims and axis argument should be the same length
            array.expand_dims(dim=['a', 'b'], axis=[1, 2, 3])
        with raises_regex(ValueError, 'Dimension x already'):
            # Should not pass the already existing dimension.
            array.expand_dims(dim=['x'])
        # raise if duplicate
        with raises_regex(ValueError, 'duplicate values.'):
            array.expand_dims(dim=['y', 'y'])
        with raises_regex(ValueError, 'duplicate values.'):
            array.expand_dims(dim=['y', 'z'], axis=[1, 1])
        with raises_regex(ValueError, 'duplicate values.'):
            array.expand_dims(dim=['y', 'z'], axis=[2, -2])

        # out of bounds error, axis must be in [-4, 3]
        with pytest.raises(IndexError):
            array.expand_dims(dim=['y', 'z'], axis=[2, 4])
        with pytest.raises(IndexError):
            array.expand_dims(dim=['y', 'z'], axis=[2, -5])
        # Does not raise an IndexError
        array.expand_dims(dim=['y', 'z'], axis=[2, -4])
        array.expand_dims(dim=['y', 'z'], axis=[2, 3])

    def test_expand_dims(self):
        array = DataArray(np.random.randn(3, 4), dims=['x', 'dim_0'],
                          coords={'x': np.linspace(0.0, 1.0, 3)},
                          attrs={'key': 'entry'})
        # pass only dim label
        actual = array.expand_dims(dim='y')
        expected = DataArray(np.expand_dims(array.values, 0),
                             dims=['y', 'x', 'dim_0'],
                             coords={'x': np.linspace(0.0, 1.0, 3)},
                             attrs={'key': 'entry'})
        assert_identical(expected, actual)
        roundtripped = actual.squeeze('y', drop=True)
        assert_identical(array, roundtripped)

        # pass multiple dims
        actual = array.expand_dims(dim=['y', 'z'])
        expected = DataArray(np.expand_dims(np.expand_dims(array.values, 0),
                                            0),
                             dims=['y', 'z', 'x', 'dim_0'],
                             coords={'x': np.linspace(0.0, 1.0, 3)},
                             attrs={'key': 'entry'})
        assert_identical(expected, actual)
        roundtripped = actual.squeeze(['y', 'z'], drop=True)
        assert_identical(array, roundtripped)

        # pass multiple dims and axis. Axis is out of order
        actual = array.expand_dims(dim=['z', 'y'], axis=[2, 1])
        expected = DataArray(np.expand_dims(np.expand_dims(array.values, 1),
                                            2),
                             dims=['x', 'y', 'z', 'dim_0'],
                             coords={'x': np.linspace(0.0, 1.0, 3)},
                             attrs={'key': 'entry'})
        assert_identical(expected, actual)
        # make sure the attrs are tracked
        assert actual.attrs['key'] == 'entry'
        roundtripped = actual.squeeze(['z', 'y'], drop=True)
        assert_identical(array, roundtripped)

        # Negative axis and they are out of order
        actual = array.expand_dims(dim=['y', 'z'], axis=[-1, -2])
        expected = DataArray(np.expand_dims(np.expand_dims(array.values, -1),
                                            -1),
                             dims=['x', 'dim_0', 'z', 'y'],
                             coords={'x': np.linspace(0.0, 1.0, 3)},
                             attrs={'key': 'entry'})
        assert_identical(expected, actual)
        assert actual.attrs['key'] == 'entry'
        roundtripped = actual.squeeze(['y', 'z'], drop=True)
        assert_identical(array, roundtripped)

    def test_expand_dims_with_scalar_coordinate(self):
        array = DataArray(np.random.randn(3, 4), dims=['x', 'dim_0'],
                          coords={'x': np.linspace(0.0, 1.0, 3), 'z': 1.0},
                          attrs={'key': 'entry'})
        actual = array.expand_dims(dim='z')
        expected = DataArray(np.expand_dims(array.values, 0),
                             dims=['z', 'x', 'dim_0'],
                             coords={'x': np.linspace(0.0, 1.0, 3),
                                     'z': np.ones(1)},
                             attrs={'key': 'entry'})
        assert_identical(expected, actual)
        roundtripped = actual.squeeze(['z'], drop=False)
        assert_identical(array, roundtripped)

    def test_set_index(self):
        indexes = [self.mindex.get_level_values(n) for n in self.mindex.names]
        coords = {idx.name: ('x', idx) for idx in indexes}
        array = DataArray(self.mda.values, coords=coords, dims='x')
        expected = self.mda.copy()
        level_3 = ('x', [1, 2, 3, 4])
        array['level_3'] = level_3
        expected['level_3'] = level_3

        obj = array.set_index(x=self.mindex.names)
        assert_identical(obj, expected)

        obj = obj.set_index(x='level_3', append=True)
        expected = array.set_index(x=['level_1', 'level_2', 'level_3'])
        assert_identical(obj, expected)

        array = array.set_index(x=['level_1', 'level_2', 'level_3'])
        assert_identical(array, expected)

        array2d = DataArray(np.random.rand(2, 2),
                            coords={'x': ('x', [0, 1]),
                                    'level': ('y', [1, 2])},
                            dims=('x', 'y'))
        with raises_regex(ValueError, 'dimension mismatch'):
            array2d.set_index(x='level')

    def test_reset_index(self):
        indexes = [self.mindex.get_level_values(n) for n in self.mindex.names]
        coords = {idx.name: ('x', idx) for idx in indexes}
        expected = DataArray(self.mda.values, coords=coords, dims='x')

        obj = self.mda.reset_index('x')
        assert_identical(obj, expected)
        obj = self.mda.reset_index(self.mindex.names)
        assert_identical(obj, expected)
        obj = self.mda.reset_index(['x', 'level_1'])
        assert_identical(obj, expected)

        coords = {'x': ('x', self.mindex.droplevel('level_1')),
                  'level_1': ('x', self.mindex.get_level_values('level_1'))}
        expected = DataArray(self.mda.values, coords=coords, dims='x')
        obj = self.mda.reset_index(['level_1'])
        assert_identical(obj, expected)

        expected = DataArray(self.mda.values, dims='x')
        obj = self.mda.reset_index('x', drop=True)
        assert_identical(obj, expected)

        array = self.mda.copy()
        array = array.reset_index(['x'], drop=True)
        assert_identical(array, expected)

        # single index
        array = DataArray([1, 2], coords={'x': ['a', 'b']}, dims='x')
        expected = DataArray([1, 2], coords={'x_': ('x', ['a', 'b'])},
                             dims='x')
        assert_identical(array.reset_index('x'), expected)

    def test_reorder_levels(self):
        midx = self.mindex.reorder_levels(['level_2', 'level_1'])
        expected = DataArray(self.mda.values, coords={'x': midx}, dims='x')

        obj = self.mda.reorder_levels(x=['level_2', 'level_1'])
        assert_identical(obj, expected)

        with pytest.warns(FutureWarning, message='The inplace argument'):
            array = self.mda.copy()
            array.reorder_levels(x=['level_2', 'level_1'], inplace=True)
            assert_identical(array, expected)

        array = DataArray([1, 2], dims='x')
        with pytest.raises(KeyError):
            array.reorder_levels(x=['level_1', 'level_2'])

        array['x'] = [0, 1]
        with raises_regex(ValueError, 'has no MultiIndex'):
            array.reorder_levels(x=['level_1', 'level_2'])

    def test_dataset_getitem(self):
        dv = self.ds['foo']
        assert_identical(dv, self.dv)

    def test_array_interface(self):
        assert_array_equal(np.asarray(self.dv), self.x)
        # test patched in methods
        assert_array_equal(self.dv.astype(float), self.v.astype(float))
        assert_array_equal(self.dv.argsort(), self.v.argsort())
        assert_array_equal(self.dv.clip(2, 3), self.v.clip(2, 3))
        # test ufuncs
        expected = deepcopy(self.ds)
        expected['foo'][:] = np.sin(self.x)
        assert_equal(expected['foo'], np.sin(self.dv))
        assert_array_equal(self.dv, np.maximum(self.v, self.dv))
        bar = Variable(['x', 'y'], np.zeros((10, 20)))
        assert_equal(self.dv, np.maximum(self.dv, bar))

    def test_is_null(self):
        x = np.random.RandomState(42).randn(5, 6)
        x[x < 0] = np.nan
        original = DataArray(x, [-np.arange(5), np.arange(6)], ['x', 'y'])
        expected = DataArray(pd.isnull(x), [-np.arange(5), np.arange(6)],
                             ['x', 'y'])
        assert_identical(expected, original.isnull())
        assert_identical(~expected, original.notnull())

    def test_math(self):
        x = self.x
        v = self.v
        a = self.dv
        # variable math was already tested extensively, so let's just make sure
        # that all types are properly converted here
        assert_equal(a, +a)
        assert_equal(a, a + 0)
        assert_equal(a, 0 + a)
        assert_equal(a, a + 0 * v)
        assert_equal(a, 0 * v + a)
        assert_equal(a, a + 0 * x)
        assert_equal(a, 0 * x + a)
        assert_equal(a, a + 0 * a)
        assert_equal(a, 0 * a + a)

    def test_math_automatic_alignment(self):
        a = DataArray(range(5), [('x', range(5))])
        b = DataArray(range(5), [('x', range(1, 6))])
        expected = DataArray(np.ones(4), [('x', [1, 2, 3, 4])])
        assert_identical(a - b, expected)

    def test_non_overlapping_dataarrays_return_empty_result(self):

        a = DataArray(range(5), [('x', range(5))])
        result = a.isel(x=slice(2)) + a.isel(x=slice(2, None))
        assert len(result['x']) == 0

    def test_empty_dataarrays_return_empty_result(self):

        a = DataArray(data=[])
        result = a * a
        assert len(result['dim_0']) == 0

    def test_inplace_math_basics(self):
        x = self.x
        a = self.dv
        v = a.variable
        b = a
        b += 1
        assert b is a
        assert b.variable is v
        assert_array_equal(b.values, x)
        assert source_ndarray(b.values) is x

    def test_inplace_math_automatic_alignment(self):
        a = DataArray(range(5), [('x', range(5))])
        b = DataArray(range(1, 6), [('x', range(1, 6))])
        with pytest.raises(xr.MergeError):
            a += b
        with pytest.raises(xr.MergeError):
            b += a

    def test_math_name(self):
        # Verify that name is preserved only when it can be done unambiguously.
        # The rule (copied from pandas.Series) is keep the current name only if
        # the other object has the same name or no name attribute and this
        # object isn't a coordinate; otherwise reset to None.
        a = self.dv
        assert (+a).name == 'foo'
        assert (a + 0).name == 'foo'
        assert (a + a.rename(None)).name is None
        assert (a + a.rename('bar')).name is None
        assert (a + a).name == 'foo'
        assert (+a['x']).name is 'x'
        assert (a['x'] + 0).name is 'x'
        assert (a + a['x']).name is None

    def test_math_with_coords(self):
        coords = {'x': [-1, -2], 'y': ['ab', 'cd', 'ef'],
                  'lat': (['x', 'y'], [[1, 2, 3], [-1, -2, -3]]),
                  'c': -999}
        orig = DataArray(np.random.randn(2, 3), coords, dims=['x', 'y'])

        actual = orig + 1
        expected = DataArray(orig.values + 1, orig.coords)
        assert_identical(expected, actual)

        actual = 1 + orig
        assert_identical(expected, actual)

        actual = orig + orig[0, 0]
        exp_coords = dict((k, v) for k, v in coords.items() if k != 'lat')
        expected = DataArray(orig.values + orig.values[0, 0],
                             exp_coords, dims=['x', 'y'])
        assert_identical(expected, actual)

        actual = orig[0, 0] + orig
        assert_identical(expected, actual)

        actual = orig[0, 0] + orig[-1, -1]
        expected = DataArray(orig.values[0, 0] + orig.values[-1, -1],
                             {'c': -999})
        assert_identical(expected, actual)

        actual = orig[:, 0] + orig[0, :]
        exp_values = orig[:, 0].values[:, None] + orig[0, :].values[None, :]
        expected = DataArray(exp_values, exp_coords, dims=['x', 'y'])
        assert_identical(expected, actual)

        actual = orig[0, :] + orig[:, 0]
        assert_identical(expected.T, actual)

        actual = orig - orig.T
        expected = DataArray(np.zeros((2, 3)), orig.coords)
        assert_identical(expected, actual)

        actual = orig.T - orig
        assert_identical(expected.T, actual)

        alt = DataArray([1, 1], {'x': [-1, -2], 'c': 'foo', 'd': 555}, 'x')
        actual = orig + alt
        expected = orig + 1
        expected.coords['d'] = 555
        del expected.coords['c']
        assert_identical(expected, actual)

        actual = alt + orig
        assert_identical(expected, actual)

    def test_index_math(self):
        orig = DataArray(range(3), dims='x', name='x')
        actual = orig + 1
        expected = DataArray(1 + np.arange(3), dims='x', name='x')
        assert_identical(expected, actual)

        # regression tests for #254
        actual = orig[0] < orig
        expected = DataArray([False, True, True], dims='x', name='x')
        assert_identical(expected, actual)

        actual = orig > orig[0]
        assert_identical(expected, actual)

    def test_dataset_math(self):
        # more comprehensive tests with multiple dataset variables
        obs = Dataset({'tmin': ('x', np.arange(5)),
                       'tmax': ('x', 10 + np.arange(5))},
                      {'x': ('x', 0.5 * np.arange(5)),
                       'loc': ('x', range(-2, 3))})

        actual = 2 * obs['tmax']
        expected = DataArray(2 * (10 + np.arange(5)), obs.coords, name='tmax')
        assert_identical(actual, expected)

        actual = obs['tmax'] - obs['tmin']
        expected = DataArray(10 * np.ones(5), obs.coords)
        assert_identical(actual, expected)

        sim = Dataset({'tmin': ('x', 1 + np.arange(5)),
                       'tmax': ('x', 11 + np.arange(5)),
                       # does *not* include 'loc' as a coordinate
                       'x': ('x', 0.5 * np.arange(5))})

        actual = sim['tmin'] - obs['tmin']
        expected = DataArray(np.ones(5), obs.coords, name='tmin')
        assert_identical(actual, expected)

        actual = -obs['tmin'] + sim['tmin']
        assert_identical(actual, expected)

        actual = sim['tmin'].copy()
        actual -= obs['tmin']
        assert_identical(actual, expected)

        actual = sim.copy()
        actual['tmin'] = sim['tmin'] - obs['tmin']
        expected = Dataset({'tmin': ('x', np.ones(5)),
                            'tmax': ('x', sim['tmax'].values)},
                           obs.coords)
        assert_identical(actual, expected)

        actual = sim.copy()
        actual['tmin'] -= obs['tmin']
        assert_identical(actual, expected)

    def test_stack_unstack(self):
        orig = DataArray([[0, 1], [2, 3]], dims=['x', 'y'], attrs={'foo': 2})
        assert_identical(orig, orig.unstack())

        actual = orig.stack(z=['x', 'y']).unstack('z').drop(['x', 'y'])
        assert_identical(orig, actual)

        dims = ['a', 'b', 'c', 'd', 'e']
        orig = xr.DataArray(np.random.rand(1, 2, 3, 2, 1), dims=dims)
        stacked = orig.stack(ab=['a', 'b'], cd=['c', 'd'])

        unstacked = stacked.unstack(['ab', 'cd'])
        roundtripped = unstacked.drop(['a', 'b', 'c', 'd']).transpose(*dims)
        assert_identical(orig, roundtripped)

        unstacked = stacked.unstack()
        roundtripped = unstacked.drop(['a', 'b', 'c', 'd']).transpose(*dims)
        assert_identical(orig, roundtripped)

    def test_stack_unstack_decreasing_coordinate(self):
        # regression test for GH980
        orig = DataArray(np.random.rand(3, 4), dims=('y', 'x'),
                         coords={'x': np.arange(4),
                                 'y': np.arange(3, 0, -1)})
        stacked = orig.stack(allpoints=['y', 'x'])
        actual = stacked.unstack('allpoints')
        assert_identical(orig, actual)

    def test_unstack_pandas_consistency(self):
        df = pd.DataFrame({'foo': range(3),
                           'x': ['a', 'b', 'b'],
                           'y': [0, 0, 1]})
        s = df.set_index(['x', 'y'])['foo']
        expected = DataArray(s.unstack(), name='foo')
        actual = DataArray(s, dims='z').unstack('z')
        assert_identical(expected, actual)

    def test_stack_nonunique_consistency(self):
        orig = DataArray([[0, 1], [2, 3]], dims=['x', 'y'],
                         coords={'x': [0, 1], 'y': [0, 0]})
        actual = orig.stack(z=['x', 'y'])
        expected = DataArray(orig.to_pandas().stack(), dims='z')
        assert_identical(expected, actual)

    def test_transpose(self):
        assert_equal(self.dv.variable.transpose(),
                     self.dv.transpose().variable)

    def test_squeeze(self):
        assert_equal(self.dv.variable.squeeze(), self.dv.squeeze().variable)

    def test_squeeze_drop(self):
        array = DataArray([1], [('x', [0])])
        expected = DataArray(1)
        actual = array.squeeze(drop=True)
        assert_identical(expected, actual)

        expected = DataArray(1, {'x': 0})
        actual = array.squeeze(drop=False)
        assert_identical(expected, actual)

        array = DataArray([[[0., 1.]]], dims=['dim_0', 'dim_1', 'dim_2'])
        expected = DataArray([[0., 1.]], dims=['dim_1', 'dim_2'])
        actual = array.squeeze(axis=0)
        assert_identical(expected, actual)

        array = DataArray([[[[0., 1.]]]], dims=[
                          'dim_0', 'dim_1', 'dim_2', 'dim_3'])
        expected = DataArray([[0., 1.]], dims=['dim_1', 'dim_3'])
        actual = array.squeeze(axis=(0, 2))
        assert_identical(expected, actual)

        array = DataArray([[[0., 1.]]], dims=['dim_0', 'dim_1', 'dim_2'])
        with pytest.raises(ValueError):
            array.squeeze(axis=0, dim='dim_1')

    def test_drop_coordinates(self):
        expected = DataArray(np.random.randn(2, 3), dims=['x', 'y'])
        arr = expected.copy()
        arr.coords['z'] = 2
        actual = arr.drop('z')
        assert_identical(expected, actual)

        with pytest.raises(ValueError):
            arr.drop('not found')

        with raises_regex(ValueError, 'cannot be found'):
            arr.drop(None)

        renamed = arr.rename('foo')
        with raises_regex(ValueError, 'cannot be found'):
            renamed.drop('foo')

    def test_drop_index_labels(self):
        arr = DataArray(np.random.randn(2, 3), coords={'y': [0, 1, 2]},
                        dims=['x', 'y'])
        actual = arr.drop([0, 1], dim='y')
        expected = arr[:, 2:]
        assert_identical(expected, actual)

    def test_dropna(self):
        x = np.random.randn(4, 4)
        x[::2, 0] = np.nan
        arr = DataArray(x, dims=['a', 'b'])

        actual = arr.dropna('a')
        expected = arr[1::2]
        assert_identical(actual, expected)

        actual = arr.dropna('b', how='all')
        assert_identical(actual, arr)

        actual = arr.dropna('a', thresh=1)
        assert_identical(actual, arr)

        actual = arr.dropna('b', thresh=3)
        expected = arr[:, 1:]
        assert_identical(actual, expected)

    def test_where(self):
        arr = DataArray(np.arange(4), dims='x')
        expected = arr.sel(x=slice(2))
        actual = arr.where(arr.x < 2, drop=True)
        assert_identical(actual, expected)

    def test_where_string(self):
        array = DataArray(['a', 'b'])
        expected = DataArray(np.array(['a', np.nan], dtype=object))
        actual = array.where([True, False])
        assert_identical(actual, expected)

    def test_cumops(self):
        coords = {'x': [-1, -2], 'y': ['ab', 'cd', 'ef'],
                  'lat': (['x', 'y'], [[1, 2, 3], [-1, -2, -3]]),
                  'c': -999}
        orig = DataArray([[-1, 0, 1], [-3, 0, 3]], coords,
                         dims=['x', 'y'])

        actual = orig.cumsum()
        expected = DataArray([[-1, -1, 0], [-4, -4, 0]], coords,
                             dims=['x', 'y'])
        assert_identical(expected, actual)

        actual = orig.cumsum('x')
        expected = DataArray([[-1, 0, 1], [-4, 0, 4]], coords,
                             dims=['x', 'y'])
        assert_identical(expected, actual)

        actual = orig.cumsum('y')
        expected = DataArray([[-1, -1, 0], [-3, -3, 0]], coords,
                             dims=['x', 'y'])
        assert_identical(expected, actual)

        actual = orig.cumprod('x')
        expected = DataArray([[-1, 0, 1], [3, 0, 3]], coords,
                             dims=['x', 'y'])
        assert_identical(expected, actual)

        actual = orig.cumprod('y')
        expected = DataArray([[-1, 0, 0], [-3, 0, 0]], coords, dims=['x', 'y'])
        assert_identical(expected, actual)

    def test_reduce(self):
        coords = {'x': [-1, -2], 'y': ['ab', 'cd', 'ef'],
                  'lat': (['x', 'y'], [[1, 2, 3], [-1, -2, -3]]),
                  'c': -999}
        orig = DataArray([[-1, 0, 1], [-3, 0, 3]], coords, dims=['x', 'y'])

        actual = orig.mean()
        expected = DataArray(0, {'c': -999})
        assert_identical(expected, actual)

        actual = orig.mean(['x', 'y'])
        assert_identical(expected, actual)

        actual = orig.mean('x')
        expected = DataArray([-2, 0, 2], {'y': coords['y'], 'c': -999}, 'y')
        assert_identical(expected, actual)

        actual = orig.mean(['x'])
        assert_identical(expected, actual)

        actual = orig.mean('y')
        expected = DataArray([0, 0], {'x': coords['x'], 'c': -999}, 'x')
        assert_identical(expected, actual)

        assert_equal(self.dv.reduce(np.mean, 'x').variable,
                     self.v.reduce(np.mean, 'x'))

        orig = DataArray([[1, 0, np.nan], [3, 0, 3]], coords, dims=['x', 'y'])
        actual = orig.count()
        expected = DataArray(5, {'c': -999})
        assert_identical(expected, actual)

        # uint support
        orig = DataArray(np.arange(6).reshape(3, 2).astype('uint'),
                         dims=['x', 'y'])
        assert orig.dtype.kind == 'u'
        actual = orig.mean(dim='x', skipna=True)
        expected = DataArray(orig.values.astype(int),
                             dims=['x', 'y']).mean('x')
        assert_equal(actual, expected)

    def test_reduce_dtype(self):
        coords = {'x': [-1, -2], 'y': ['ab', 'cd', 'ef'],
                  'lat': (['x', 'y'], [[1, 2, 3], [-1, -2, -3]]),
                  'c': -999}
        orig = DataArray([[-1, 0, 1], [-3, 0, 3]], coords, dims=['x', 'y'])

        for dtype in [np.float16, np.float32, np.float64]:
            assert orig.astype(float).mean(dtype=dtype).dtype == dtype

    def test_reduce_out(self):
        coords = {'x': [-1, -2], 'y': ['ab', 'cd', 'ef'],
                  'lat': (['x', 'y'], [[1, 2, 3], [-1, -2, -3]]),
                  'c': -999}
        orig = DataArray([[-1, 0, 1], [-3, 0, 3]], coords, dims=['x', 'y'])

        with pytest.raises(TypeError):
            orig.mean(out=np.ones(orig.shape))

    # skip due to bug in older versions of numpy.nanpercentile
    def test_quantile(self):
        for q in [0.25, [0.50], [0.25, 0.75]]:
            for axis, dim in zip([None, 0, [0], [0, 1]],
                                 [None, 'x', ['x'], ['x', 'y']]):
                actual = self.dv.quantile(q, dim=dim)
                expected = np.nanpercentile(self.dv.values, np.array(q) * 100,
                                            axis=axis)
                np.testing.assert_allclose(actual.values, expected)

    def test_reduce_keep_attrs(self):
        # Test dropped attrs
        vm = self.va.mean()
        assert len(vm.attrs) == 0
        assert vm.attrs == OrderedDict()

        # Test kept attrs
        vm = self.va.mean(keep_attrs=True)
        assert len(vm.attrs) == len(self.attrs)
        assert vm.attrs == self.attrs

    def test_assign_attrs(self):
        expected = DataArray([], attrs=dict(a=1, b=2))
        expected.attrs['a'] = 1
        expected.attrs['b'] = 2
        new = DataArray([])
        actual = DataArray([]).assign_attrs(a=1, b=2)
        assert_identical(actual, expected)
        assert new.attrs == {}

        expected.attrs['c'] = 3
        new_actual = actual.assign_attrs({'c': 3})
        assert_identical(new_actual, expected)
        assert actual.attrs == {'a': 1, 'b': 2}

    def test_fillna(self):
        a = DataArray([np.nan, 1, np.nan, 3], coords={'x': range(4)}, dims='x')
        actual = a.fillna(-1)
        expected = DataArray([-1, 1, -1, 3], coords={'x': range(4)}, dims='x')
        assert_identical(expected, actual)

        b = DataArray(range(4), coords={'x': range(4)}, dims='x')
        actual = a.fillna(b)
        expected = b.copy()
        assert_identical(expected, actual)

        actual = a.fillna(range(4))
        assert_identical(expected, actual)

        actual = a.fillna(b[:3])
        assert_identical(expected, actual)

        actual = a.fillna(b[:0])
        assert_identical(a, actual)

        with raises_regex(TypeError, 'fillna on a DataArray'):
            a.fillna({0: 0})

        with raises_regex(ValueError, 'broadcast'):
            a.fillna([1, 2])

        fill_value = DataArray([0, 1], dims='y')
        actual = a.fillna(fill_value)
        expected = DataArray([[0, 1], [1, 1], [0, 1], [3, 3]],
                             coords={'x': range(4)}, dims=('x', 'y'))
        assert_identical(expected, actual)

        expected = b.copy()
        for target in [a, expected]:
            target.coords['b'] = ('x', [0, 0, 1, 1])
        actual = a.groupby('b').fillna(DataArray([0, 2], dims='b'))
        assert_identical(expected, actual)

    def test_groupby_iter(self):
        for ((act_x, act_dv), (exp_x, exp_ds)) in \
                zip(self.dv.groupby('y'), self.ds.groupby('y')):
            assert exp_x == act_x
            assert_identical(exp_ds['foo'], act_dv)
        for ((_, exp_dv), act_dv) in zip(self.dv.groupby('x'), self.dv):
            assert_identical(exp_dv, act_dv)

    def make_groupby_example_array(self):
        da = self.dv.copy()
        da.coords['abc'] = ('y', np.array(['a'] * 9 + ['c'] + ['b'] * 10))
        da.coords['y'] = 20 + 100 * da['y']
        return da

    def test_groupby_properties(self):
        grouped = self.make_groupby_example_array().groupby('abc')
        expected_groups = {'a': range(0, 9), 'c': [9], 'b': range(10, 20)}
        assert expected_groups.keys() == grouped.groups.keys()
        for key in expected_groups:
            assert_array_equal(expected_groups[key], grouped.groups[key])
        assert 3 == len(grouped)

    def test_groupby_apply_identity(self):
        expected = self.make_groupby_example_array()
        idx = expected.coords['y']

        def identity(x):
            return x

        for g in ['x', 'y', 'abc', idx]:
            for shortcut in [False, True]:
                for squeeze in [False, True]:
                    grouped = expected.groupby(g, squeeze=squeeze)
                    actual = grouped.apply(identity, shortcut=shortcut)
                    assert_identical(expected, actual)

    def test_groupby_sum(self):
        array = self.make_groupby_example_array()
        grouped = array.groupby('abc')

        expected_sum_all = Dataset(
            {'foo': Variable(['abc'], np.array([self.x[:, :9].sum(),
                                                self.x[:, 10:].sum(),
                                                self.x[:, 9:10].sum()]).T),
             'abc': Variable(['abc'], np.array(['a', 'b', 'c']))})['foo']
        assert_allclose(expected_sum_all, grouped.reduce(np.sum, dim=ALL_DIMS))
        assert_allclose(expected_sum_all, grouped.sum(ALL_DIMS))

        expected = DataArray([array['y'].values[idx].sum() for idx
                              in [slice(9), slice(10, None), slice(9, 10)]],
                             [['a', 'b', 'c']], ['abc'])
        actual = array['y'].groupby('abc').apply(np.sum)
        assert_allclose(expected, actual)
        actual = array['y'].groupby('abc').sum(ALL_DIMS)
        assert_allclose(expected, actual)

        expected_sum_axis1 = Dataset(
            {'foo': (['x', 'abc'], np.array([self.x[:, :9].sum(1),
                                             self.x[:, 10:].sum(1),
                                             self.x[:, 9:10].sum(1)]).T),
             'abc': Variable(['abc'], np.array(['a', 'b', 'c']))})['foo']
        assert_allclose(expected_sum_axis1, grouped.reduce(np.sum, 'y'))
        assert_allclose(expected_sum_axis1, grouped.sum('y'))

    def test_groupby_warning(self):
        array = self.make_groupby_example_array()
        grouped = array.groupby('y')
        with pytest.warns(FutureWarning):
            grouped.sum()

    @pytest.mark.skipif(LooseVersion(xr.__version__) < LooseVersion('0.12'),
                        reason="not to forget the behavior change")
    def test_groupby_sum_default(self):
        array = self.make_groupby_example_array()
        grouped = array.groupby('abc')

        expected_sum_all = Dataset(
            {'foo': Variable(['x', 'abc'],
                             np.array([self.x[:, :9].sum(axis=-1),
                                       self.x[:, 10:].sum(axis=-1),
                                       self.x[:, 9:10].sum(axis=-1)]).T),
             'abc': Variable(['abc'], np.array(['a', 'b', 'c']))})['foo']

        assert_allclose(expected_sum_all, grouped.sum())

    def test_groupby_count(self):
        array = DataArray(
            [0, 0, np.nan, np.nan, 0, 0],
            coords={'cat': ('x', ['a', 'b', 'b', 'c', 'c', 'c'])},
            dims='x')
        actual = array.groupby('cat').count()
        expected = DataArray([1, 1, 2], coords=[('cat', ['a', 'b', 'c'])])
        assert_identical(actual, expected)

    @pytest.mark.skip('needs to be fixed for shortcut=False, keep_attrs=False')
    def test_groupby_reduce_attrs(self):
        array = self.make_groupby_example_array()
        array.attrs['foo'] = 'bar'

        for shortcut in [True, False]:
            for keep_attrs in [True, False]:
                print('shortcut=%s, keep_attrs=%s' % (shortcut, keep_attrs))
                actual = array.groupby('abc').reduce(
                    np.mean, keep_attrs=keep_attrs, shortcut=shortcut)
                expected = array.groupby('abc').mean()
                if keep_attrs:
                    expected.attrs['foo'] = 'bar'
                assert_identical(expected, actual)

    def test_groupby_apply_center(self):
        def center(x):
            return x - np.mean(x)

        array = self.make_groupby_example_array()
        grouped = array.groupby('abc')

        expected_ds = array.to_dataset()
        exp_data = np.hstack([center(self.x[:, :9]),
                              center(self.x[:, 9:10]),
                              center(self.x[:, 10:])])
        expected_ds['foo'] = (['x', 'y'], exp_data)
        expected_centered = expected_ds['foo']
        assert_allclose(expected_centered, grouped.apply(center))

    def test_groupby_apply_ndarray(self):
        # regression test for #326
        array = self.make_groupby_example_array()
        grouped = array.groupby('abc')
        actual = grouped.apply(np.asarray)
        assert_equal(array, actual)

    def test_groupby_apply_changes_metadata(self):
        def change_metadata(x):
            x.coords['x'] = x.coords['x'] * 2
            x.attrs['fruit'] = 'lemon'
            return x

        array = self.make_groupby_example_array()
        grouped = array.groupby('abc')
        actual = grouped.apply(change_metadata)
        expected = array.copy()
        expected = change_metadata(expected)
        assert_equal(expected, actual)

    def test_groupby_math(self):
        array = self.make_groupby_example_array()
        for squeeze in [True, False]:
            grouped = array.groupby('x', squeeze=squeeze)

            expected = array + array.coords['x']
            actual = grouped + array.coords['x']
            assert_identical(expected, actual)

            actual = array.coords['x'] + grouped
            assert_identical(expected, actual)

            ds = array.coords['x'].to_dataset(name='X')
            expected = array + ds
            actual = grouped + ds
            assert_identical(expected, actual)

            actual = ds + grouped
            assert_identical(expected, actual)

        grouped = array.groupby('abc')
        expected_agg = (grouped.mean(ALL_DIMS) - np.arange(3)).rename(None)
        actual = grouped - DataArray(range(3), [('abc', ['a', 'b', 'c'])])
        actual_agg = actual.groupby('abc').mean(ALL_DIMS)
        assert_allclose(expected_agg, actual_agg)

        with raises_regex(TypeError, 'only support binary ops'):
            grouped + 1
        with raises_regex(TypeError, 'only support binary ops'):
            grouped + grouped
        with raises_regex(TypeError, 'in-place operations'):
            array += grouped

    def test_groupby_math_not_aligned(self):
        array = DataArray(range(4), {'b': ('x', [0, 0, 1, 1]),
                                     'x': [0, 1, 2, 3]},
                          dims='x')
        other = DataArray([10], coords={'b': [0]}, dims='b')
        actual = array.groupby('b') + other
        expected = DataArray([10, 11, np.nan, np.nan], array.coords)
        assert_identical(expected, actual)

        other = DataArray([10], coords={'c': 123, 'b': [0]}, dims='b')
        actual = array.groupby('b') + other
        expected.coords['c'] = (['x'], [123] * 2 + [np.nan] * 2)
        assert_identical(expected, actual)

        other = Dataset({'a': ('b', [10])}, {'b': [0]})
        actual = array.groupby('b') + other
        expected = Dataset({'a': ('x', [10, 11, np.nan, np.nan])},
                           array.coords)
        assert_identical(expected, actual)

    def test_groupby_restore_dim_order(self):
        array = DataArray(np.random.randn(5, 3),
                          coords={'a': ('x', range(5)), 'b': ('y', range(3))},
                          dims=['x', 'y'])
        for by, expected_dims in [('x', ('x', 'y')),
                                  ('y', ('x', 'y')),
                                  ('a', ('a', 'y')),
                                  ('b', ('x', 'b'))]:
            result = array.groupby(by).apply(lambda x: x.squeeze())
            assert result.dims == expected_dims

    def test_groupby_first_and_last(self):
        array = DataArray([1, 2, 3, 4, 5], dims='x')
        by = DataArray(['a'] * 2 + ['b'] * 3, dims='x', name='ab')

        expected = DataArray([1, 3], [('ab', ['a', 'b'])])
        actual = array.groupby(by).first()
        assert_identical(expected, actual)

        expected = DataArray([2, 5], [('ab', ['a', 'b'])])
        actual = array.groupby(by).last()
        assert_identical(expected, actual)

        array = DataArray(np.random.randn(5, 3), dims=['x', 'y'])
        expected = DataArray(array[[0, 2]], {'ab': ['a', 'b']}, ['ab', 'y'])
        actual = array.groupby(by).first()
        assert_identical(expected, actual)

        actual = array.groupby('x').first()
        expected = array  # should be a no-op
        assert_identical(expected, actual)

    def make_groupby_multidim_example_array(self):
        return DataArray([[[0, 1], [2, 3]], [[5, 10], [15, 20]]],
                         coords={'lon': (['ny', 'nx'], [[30, 40], [40, 50]]),
                                 'lat': (['ny', 'nx'], [[10, 10], [20, 20]])},
                         dims=['time', 'ny', 'nx'])

    def test_groupby_multidim(self):
        array = self.make_groupby_multidim_example_array()
        for dim, expected_sum in [
                ('lon', DataArray([5, 28, 23],
                                  coords=[('lon', [30., 40., 50.])])),
                ('lat', DataArray([16, 40], coords=[('lat', [10., 20.])]))]:
            actual_sum = array.groupby(dim).sum(ALL_DIMS)
            assert_identical(expected_sum, actual_sum)

    def test_groupby_multidim_apply(self):
        array = self.make_groupby_multidim_example_array()
        actual = array.groupby('lon').apply(lambda x: x - x.mean())
        expected = DataArray([[[-2.5, -6.], [-5., -8.5]],
                              [[2.5, 3.], [8., 8.5]]],
                             coords=array.coords, dims=array.dims)
        assert_identical(expected, actual)

    def test_groupby_bins(self):
        array = DataArray(np.arange(4), dims='dim_0')
        # the first value should not be part of any group ("right" binning)
        array[0] = 99
        # bins follow conventions for pandas.cut
        # http://pandas.pydata.org/pandas-docs/stable/generated/pandas.cut.html
        bins = [0, 1.5, 5]
        bin_coords = pd.cut(array['dim_0'], bins).categories
        expected = DataArray([1, 5], dims='dim_0_bins',
                             coords={'dim_0_bins': bin_coords})
        # the problem with this is that it overwrites the dimensions of array!
        # actual = array.groupby('dim_0', bins=bins).sum()
        actual = array.groupby_bins('dim_0', bins).apply(lambda x: x.sum())
        assert_identical(expected, actual)
        # make sure original array dims are unchanged
        assert len(array.dim_0) == 4

    def test_groupby_bins_empty(self):
        array = DataArray(np.arange(4), [('x', range(4))])
        # one of these bins will be empty
        bins = [0, 4, 5]
        bin_coords = pd.cut(array['x'], bins).categories
        actual = array.groupby_bins('x', bins).sum()
        expected = DataArray([6, np.nan], dims='x_bins',
                             coords={'x_bins': bin_coords})
        assert_identical(expected, actual)
        # make sure original array is unchanged
        # (was a problem in earlier versions)
        assert len(array.x) == 4

    def test_groupby_bins_multidim(self):
        array = self.make_groupby_multidim_example_array()
        bins = [0, 15, 20]
        bin_coords = pd.cut(array['lat'].values.flat, bins).categories
        expected = DataArray([16, 40], dims='lat_bins',
                             coords={'lat_bins': bin_coords})
        actual = array.groupby_bins('lat', bins).apply(lambda x: x.sum())
        assert_identical(expected, actual)
        # modify the array coordinates to be non-monotonic after unstacking
        array['lat'].data = np.array([[10., 20.], [20., 10.]])
        expected = DataArray([28, 28], dims='lat_bins',
                             coords={'lat_bins': bin_coords})
        actual = array.groupby_bins('lat', bins).apply(lambda x: x.sum())
        assert_identical(expected, actual)

    def test_groupby_bins_sort(self):
        data = xr.DataArray(
            np.arange(100), dims='x',
            coords={'x': np.linspace(-100, 100, num=100)})
        binned_mean = data.groupby_bins('x', bins=11).mean()
        assert binned_mean.to_index().is_monotonic

    def test_resample(self):
        times = pd.date_range('2000-01-01', freq='6H', periods=10)
        array = DataArray(np.arange(10), [('time', times)])

        actual = array.resample(time='24H').mean()
        expected = DataArray(array.to_series().resample('24H').mean())
        assert_identical(expected, actual)

        actual = array.resample(time='24H').reduce(np.mean)
        assert_identical(expected, actual)

        actual = array.resample(time='24H', loffset='-12H').mean()
        expected = DataArray(array.to_series().resample('24H', loffset='-12H')
                             .mean())
        assert_identical(expected, actual)

        with raises_regex(ValueError, 'index must be monotonic'):
            array[[2, 0, 1]].resample(time='1D')

    def test_da_resample_func_args(self):

        def func(arg1, arg2, arg3=0.):
            return arg1.mean('time') + arg2 + arg3

        times = pd.date_range('2000', periods=3, freq='D')
        da = xr.DataArray([1., 1., 1.], coords=[times], dims=['time'])
        expected = xr.DataArray([3., 3., 3.], coords=[times], dims=['time'])
        actual = da.resample(time='D').apply(func, args=(1.,), arg3=1.)
        assert_identical(actual, expected)

    @requires_cftime
    def test_resample_cftimeindex(self):
        cftime = _import_cftime()
        times = cftime.num2date(np.arange(12), units='hours since 0001-01-01',
                                calendar='noleap')
        array = DataArray(np.arange(12), [('time', times)])

        with raises_regex(NotImplementedError, 'to_datetimeindex'):
            array.resample(time='6H').mean()

    def test_resample_first(self):
        times = pd.date_range('2000-01-01', freq='6H', periods=10)
        array = DataArray(np.arange(10), [('time', times)])

        actual = array.resample(time='1D').first()
        expected = DataArray([0, 4, 8], [('time', times[::4])])
        assert_identical(expected, actual)

        # verify that labels don't use the first value
        actual = array.resample(time='24H').first()
        expected = DataArray(array.to_series().resample('24H').first())
        assert_identical(expected, actual)

        # missing values
        array = array.astype(float)
        array[:2] = np.nan
        actual = array.resample(time='1D').first()
        expected = DataArray([2, 4, 8], [('time', times[::4])])
        assert_identical(expected, actual)

        actual = array.resample(time='1D').first(skipna=False)
        expected = DataArray([np.nan, 4, 8], [('time', times[::4])])
        assert_identical(expected, actual)

        # regression test for http://stackoverflow.com/questions/33158558/
        array = Dataset({'time': times})['time']
        actual = array.resample(time='1D').last()
        expected_times = pd.to_datetime(['2000-01-01T18', '2000-01-02T18',
                                         '2000-01-03T06'])
        expected = DataArray(expected_times, [('time', times[::4])],
                             name='time')
        assert_identical(expected, actual)

    def test_resample_bad_resample_dim(self):
        times = pd.date_range('2000-01-01', freq='6H', periods=10)
        array = DataArray(np.arange(10), [('__resample_dim__', times)])
        with raises_regex(ValueError, 'Proxy resampling dimension'):
            array.resample(**{'__resample_dim__': '1D'}).first()

    @requires_scipy
    def test_resample_drop_nondim_coords(self):
        xs = np.arange(6)
        ys = np.arange(3)
        times = pd.date_range('2000-01-01', freq='6H', periods=5)
        data = np.tile(np.arange(5), (6, 3, 1))
        xx, yy = np.meshgrid(xs * 5, ys * 2.5)
        tt = np.arange(len(times), dtype=int)
        array = DataArray(data,
                          {'time': times, 'x': xs, 'y': ys},
                          ('x', 'y', 'time'))
        xcoord = DataArray(xx.T, {'x': xs, 'y': ys}, ('x', 'y'))
        ycoord = DataArray(yy.T, {'x': xs, 'y': ys}, ('x', 'y'))
        tcoord = DataArray(tt, {'time': times}, ('time', ))
        ds = Dataset({'data': array, 'xc': xcoord,
                      'yc': ycoord, 'tc': tcoord})
        ds = ds.set_coords(['xc', 'yc', 'tc'])

        # Select the data now, with the auxiliary coordinates in place
        array = ds['data']

        # Re-sample
        actual = array.resample(time="12H").mean('time')
        assert 'tc' not in actual.coords

        # Up-sample - filling
        actual = array.resample(time="1H").ffill()
        assert 'tc' not in actual.coords

        # Up-sample - interpolation
        actual = array.resample(time="1H").interpolate('linear')
        assert 'tc' not in actual.coords

    def test_resample_keep_attrs(self):
        times = pd.date_range('2000-01-01', freq='6H', periods=10)
        array = DataArray(np.ones(10), [('time', times)])
        array.attrs['meta'] = 'data'

        result = array.resample(time='1D').mean(keep_attrs=True)
        expected = DataArray([1, 1, 1], [('time', times[::4])],
                             attrs=array.attrs)
        assert_identical(result, expected)

    def test_resample_skipna(self):
        times = pd.date_range('2000-01-01', freq='6H', periods=10)
        array = DataArray(np.ones(10), [('time', times)])
        array[1] = np.nan

        result = array.resample(time='1D').mean(skipna=False)
        expected = DataArray([np.nan, 1, 1], [('time', times[::4])])
        assert_identical(result, expected)

    def test_upsample(self):
        times = pd.date_range('2000-01-01', freq='6H', periods=5)
        array = DataArray(np.arange(5), [('time', times)])

        # Forward-fill
        actual = array.resample(time='3H').ffill()
        expected = DataArray(array.to_series().resample('3H').ffill())
        assert_identical(expected, actual)

        # Backward-fill
        actual = array.resample(time='3H').bfill()
        expected = DataArray(array.to_series().resample('3H').bfill())
        assert_identical(expected, actual)

        # As frequency
        actual = array.resample(time='3H').asfreq()
        expected = DataArray(array.to_series().resample('3H').asfreq())
        assert_identical(expected, actual)

        # Pad
        actual = array.resample(time='3H').pad()
        expected = DataArray(array.to_series().resample('3H').pad())
        assert_identical(expected, actual)

        # Nearest
        rs = array.resample(time='3H')
        actual = rs.nearest()
        new_times = rs._full_index
        expected = DataArray(
            array.reindex(time=new_times, method='nearest')
        )
        assert_identical(expected, actual)

    def test_upsample_nd(self):
        # Same as before, but now we try on multi-dimensional DataArrays.
        xs = np.arange(6)
        ys = np.arange(3)
        times = pd.date_range('2000-01-01', freq='6H', periods=5)
        data = np.tile(np.arange(5), (6, 3, 1))
        array = DataArray(data,
                          {'time': times, 'x': xs, 'y': ys},
                          ('x', 'y', 'time'))

        # Forward-fill
        actual = array.resample(time='3H').ffill()
        expected_data = np.repeat(data, 2, axis=-1)
        expected_times = times.to_series().resample('3H').asfreq().index
        expected_data = expected_data[..., :len(expected_times)]
        expected = DataArray(expected_data,
                             {'time': expected_times, 'x': xs, 'y': ys},
                             ('x', 'y', 'time'))
        assert_identical(expected, actual)

        # Backward-fill
        actual = array.resample(time='3H').ffill()
        expected_data = np.repeat(np.flipud(data.T).T, 2, axis=-1)
        expected_data = np.flipud(expected_data.T).T
        expected_times = times.to_series().resample('3H').asfreq().index
        expected_data = expected_data[..., :len(expected_times)]
        expected = DataArray(expected_data,
                             {'time': expected_times, 'x': xs, 'y': ys},
                             ('x', 'y', 'time'))
        assert_identical(expected, actual)

        # As frequency
        actual = array.resample(time='3H').asfreq()
        expected_data = np.repeat(data, 2, axis=-1).astype(float)[..., :-1]
        expected_data[..., 1::2] = np.nan
        expected_times = times.to_series().resample('3H').asfreq().index
        expected = DataArray(expected_data,
                             {'time': expected_times, 'x': xs, 'y': ys},
                             ('x', 'y', 'time'))
        assert_identical(expected, actual)

        # Pad
        actual = array.resample(time='3H').pad()
        expected_data = np.repeat(data, 2, axis=-1)
        expected_data[..., 1::2] = expected_data[..., ::2]
        expected_data = expected_data[..., :-1]
        expected_times = times.to_series().resample('3H').asfreq().index
        expected = DataArray(expected_data,
                             {'time': expected_times, 'x': xs, 'y': ys},
                             ('x', 'y', 'time'))
        assert_identical(expected, actual)

    @requires_scipy
    def test_upsample_interpolate(self):
        from scipy.interpolate import interp1d
        xs = np.arange(6)
        ys = np.arange(3)
        times = pd.date_range('2000-01-01', freq='6H', periods=5)

        z = np.arange(5)**2
        data = np.tile(z, (6, 3, 1))
        array = DataArray(data,
                          {'time': times, 'x': xs, 'y': ys},
                          ('x', 'y', 'time'))

        expected_times = times.to_series().resample('1H').asfreq().index
        # Split the times into equal sub-intervals to simulate the 6 hour
        # to 1 hour up-sampling
        new_times_idx = np.linspace(0, len(times) - 1, len(times) * 5)
        for kind in ['linear', 'nearest', 'zero', 'slinear', 'quadratic',
                     'cubic']:
            actual = array.resample(time='1H').interpolate(kind)
            f = interp1d(np.arange(len(times)), data, kind=kind, axis=-1,
                         bounds_error=True, assume_sorted=True)
            expected_data = f(new_times_idx)
            expected = DataArray(expected_data,
                                 {'time': expected_times, 'x': xs, 'y': ys},
                                 ('x', 'y', 'time'))
            # Use AllClose because there are some small differences in how
            # we upsample timeseries versus the integer indexing as I've
            # done here due to floating point arithmetic
            assert_allclose(expected, actual, rtol=1e-16)

    @requires_scipy
    def test_upsample_interpolate_regression_1605(self):
        dates = pd.date_range('2016-01-01', '2016-03-31', freq='1D')
        expected = xr.DataArray(np.random.random((len(dates), 2, 3)),
                                dims=('time', 'x', 'y'),
                                coords={'time': dates})
        actual = expected.resample(time='1D').interpolate('linear')
        assert_allclose(actual, expected, rtol=1e-16)

    @requires_dask
    @requires_scipy
    def test_upsample_interpolate_dask(self):
        import dask.array as da

        times = pd.date_range('2000-01-01', freq='6H', periods=5)
        xs = np.arange(6)
        ys = np.arange(3)

        z = np.arange(5)**2
        data = da.from_array(np.tile(z, (6, 3, 1)), (1, 3, 1))
        array = DataArray(data,
                          {'time': times, 'x': xs, 'y': ys},
                          ('x', 'y', 'time'))

        with raises_regex(TypeError,
                          "dask arrays are not yet supported"):
            array.resample(time='1H').interpolate('linear')

    def test_align(self):
        array = DataArray(np.random.random((6, 8)),
                          coords={'x': list('abcdef')}, dims=['x', 'y'])
        array1, array2 = align(array, array[:5], join='inner')
        assert_identical(array1, array[:5])
        assert_identical(array2, array[:5])

    def test_align_dtype(self):
        # regression test for #264
        x1 = np.arange(30)
        x2 = np.arange(5, 35)
        a = DataArray(np.random.random((30,)).astype(np.float32), [('x', x1)])
        b = DataArray(np.random.random((30,)).astype(np.float32), [('x', x2)])
        c, d = align(a, b, join='outer')
        assert c.dtype == np.float32

    def test_align_copy(self):
        x = DataArray([1, 2, 3], coords=[('a', [1, 2, 3])])
        y = DataArray([1, 2], coords=[('a', [3, 1])])

        expected_x2 = x
        expected_y2 = DataArray([2, np.nan, 1], coords=[('a', [1, 2, 3])])

        x2, y2 = align(x, y, join='outer', copy=False)
        assert_identical(expected_x2, x2)
        assert_identical(expected_y2, y2)
        assert source_ndarray(x2.data) is source_ndarray(x.data)

        x2, y2 = align(x, y, join='outer', copy=True)
        assert_identical(expected_x2, x2)
        assert_identical(expected_y2, y2)
        assert source_ndarray(x2.data) is not source_ndarray(x.data)

        # Trivial align - 1 element
        x = DataArray([1, 2, 3], coords=[('a', [1, 2, 3])])
        x2, = align(x, copy=False)
        assert_identical(x, x2)
        assert source_ndarray(x2.data) is source_ndarray(x.data)

        x2, = align(x, copy=True)
        assert_identical(x, x2)
        assert source_ndarray(x2.data) is not source_ndarray(x.data)

    def test_align_exclude(self):
        x = DataArray([[1, 2], [3, 4]],
                      coords=[('a', [-1, -2]), ('b', [3, 4])])
        y = DataArray([[1, 2], [3, 4]],
                      coords=[('a', [-1, 20]), ('b', [5, 6])])
        z = DataArray([1], dims=['a'], coords={'a': [20], 'b': 7})

        x2, y2, z2 = align(x, y, z, join='outer', exclude=['b'])
        expected_x2 = DataArray([[3, 4], [1, 2], [np.nan, np.nan]],
                                coords=[('a', [-2, -1, 20]), ('b', [3, 4])])
        expected_y2 = DataArray([[np.nan, np.nan], [1, 2], [3, 4]],
                                coords=[('a', [-2, -1, 20]), ('b', [5, 6])])
        expected_z2 = DataArray([np.nan, np.nan, 1], dims=['a'],
                                coords={'a': [-2, -1, 20], 'b': 7})
        assert_identical(expected_x2, x2)
        assert_identical(expected_y2, y2)
        assert_identical(expected_z2, z2)

    def test_align_indexes(self):
        x = DataArray([1, 2, 3], coords=[('a', [-1, 10, -2])])
        y = DataArray([1, 2], coords=[('a', [-2, -1])])

        x2, y2 = align(x, y, join='outer', indexes={'a': [10, -1, -2]})
        expected_x2 = DataArray([2, 1, 3], coords=[('a', [10, -1, -2])])
        expected_y2 = DataArray([np.nan, 2, 1], coords=[('a', [10, -1, -2])])
        assert_identical(expected_x2, x2)
        assert_identical(expected_y2, y2)

        x2, = align(x, join='outer', indexes={'a': [-2, 7, 10, -1]})
        expected_x2 = DataArray([3, np.nan, 2, 1],
                                coords=[('a', [-2, 7, 10, -1])])
        assert_identical(expected_x2, x2)

    def test_align_without_indexes_exclude(self):
        arrays = [DataArray([1, 2, 3], dims=['x']),
                  DataArray([1, 2], dims=['x'])]
        result0, result1 = align(*arrays, exclude=['x'])
        assert_identical(result0, arrays[0])
        assert_identical(result1, arrays[1])

    def test_align_mixed_indexes(self):
        array_no_coord = DataArray([1, 2], dims=['x'])
        array_with_coord = DataArray([1, 2], coords=[('x', ['a', 'b'])])
        result0, result1 = align(array_no_coord, array_with_coord)
        assert_identical(result0, array_with_coord)
        assert_identical(result1, array_with_coord)

        result0, result1 = align(array_no_coord, array_with_coord,
                                 exclude=['x'])
        assert_identical(result0, array_no_coord)
        assert_identical(result1, array_with_coord)

    def test_align_without_indexes_errors(self):
        with raises_regex(ValueError, 'cannot be aligned'):
            align(DataArray([1, 2, 3], dims=['x']),
                  DataArray([1, 2], dims=['x']))

        with raises_regex(ValueError, 'cannot be aligned'):
            align(DataArray([1, 2, 3], dims=['x']),
                  DataArray([1, 2], coords=[('x', [0, 1])]))

    def test_broadcast_arrays(self):
        x = DataArray([1, 2], coords=[('a', [-1, -2])], name='x')
        y = DataArray([1, 2], coords=[('b', [3, 4])], name='y')
        x2, y2 = broadcast(x, y)
        expected_coords = [('a', [-1, -2]), ('b', [3, 4])]
        expected_x2 = DataArray([[1, 1], [2, 2]], expected_coords, name='x')
        expected_y2 = DataArray([[1, 2], [1, 2]], expected_coords, name='y')
        assert_identical(expected_x2, x2)
        assert_identical(expected_y2, y2)

        x = DataArray(np.random.randn(2, 3), dims=['a', 'b'])
        y = DataArray(np.random.randn(3, 2), dims=['b', 'a'])
        x2, y2 = broadcast(x, y)
        expected_x2 = x
        expected_y2 = y.T
        assert_identical(expected_x2, x2)
        assert_identical(expected_y2, y2)

    def test_broadcast_arrays_misaligned(self):
        # broadcast on misaligned coords must auto-align
        x = DataArray([[1, 2], [3, 4]],
                      coords=[('a', [-1, -2]), ('b', [3, 4])])
        y = DataArray([1, 2], coords=[('a', [-1, 20])])
        expected_x2 = DataArray([[3, 4], [1, 2], [np.nan, np.nan]],
                                coords=[('a', [-2, -1, 20]), ('b', [3, 4])])
        expected_y2 = DataArray([[np.nan, np.nan], [1, 1], [2, 2]],
                                coords=[('a', [-2, -1, 20]), ('b', [3, 4])])
        x2, y2 = broadcast(x, y)
        assert_identical(expected_x2, x2)
        assert_identical(expected_y2, y2)

    def test_broadcast_arrays_nocopy(self):
        # Test that input data is not copied over in case
        # no alteration is needed
        x = DataArray([1, 2], coords=[('a', [-1, -2])], name='x')
        y = DataArray(3, name='y')
        expected_x2 = DataArray([1, 2], coords=[('a', [-1, -2])], name='x')
        expected_y2 = DataArray([3, 3], coords=[('a', [-1, -2])], name='y')

        x2, y2 = broadcast(x, y)
        assert_identical(expected_x2, x2)
        assert_identical(expected_y2, y2)
        assert source_ndarray(x2.data) is source_ndarray(x.data)

        # single-element broadcast (trivial case)
        x2, = broadcast(x)
        assert_identical(x, x2)
        assert source_ndarray(x2.data) is source_ndarray(x.data)

    def test_broadcast_arrays_exclude(self):
        x = DataArray([[1, 2], [3, 4]],
                      coords=[('a', [-1, -2]), ('b', [3, 4])])
        y = DataArray([1, 2], coords=[('a', [-1, 20])])
        z = DataArray(5, coords={'b': 5})

        x2, y2, z2 = broadcast(x, y, z, exclude=['b'])
        expected_x2 = DataArray([[3, 4], [1, 2], [np.nan, np.nan]],
                                coords=[('a', [-2, -1, 20]), ('b', [3, 4])])
        expected_y2 = DataArray([np.nan, 1, 2], coords=[('a', [-2, -1, 20])])
        expected_z2 = DataArray([5, 5, 5], dims=['a'],
                                coords={'a': [-2, -1, 20], 'b': 5})
        assert_identical(expected_x2, x2)
        assert_identical(expected_y2, y2)
        assert_identical(expected_z2, z2)

    def test_broadcast_coordinates(self):
        # regression test for GH649
        ds = Dataset({'a': (['x', 'y'], np.ones((5, 6)))})
        x_bc, y_bc, a_bc = broadcast(ds.x, ds.y, ds.a)
        assert_identical(ds.a, a_bc)

        X, Y = np.meshgrid(np.arange(5), np.arange(6), indexing='ij')
        exp_x = DataArray(X, dims=['x', 'y'], name='x')
        exp_y = DataArray(Y, dims=['x', 'y'], name='y')
        assert_identical(exp_x, x_bc)
        assert_identical(exp_y, y_bc)

    def test_to_pandas(self):
        # 0d
        actual = DataArray(42).to_pandas()
        expected = np.array(42)
        assert_array_equal(actual, expected)

        # 1d
        values = np.random.randn(3)
        index = pd.Index(['a', 'b', 'c'], name='x')
        da = DataArray(values, coords=[index])
        actual = da.to_pandas()
        assert_array_equal(actual.values, values)
        assert_array_equal(actual.index, index)
        assert_array_equal(actual.index.name, 'x')

        # 2d
        values = np.random.randn(3, 2)
        da = DataArray(values, coords=[('x', ['a', 'b', 'c']), ('y', [0, 1])],
                       name='foo')
        actual = da.to_pandas()
        assert_array_equal(actual.values, values)
        assert_array_equal(actual.index, ['a', 'b', 'c'])
        assert_array_equal(actual.columns, [0, 1])

        # roundtrips
        for shape in [(3,), (3, 4), (3, 4, 5)]:
            if len(shape) > 2 and not hasattr(pd, 'Panel'):
                continue
            dims = list('abc')[:len(shape)]
            da = DataArray(np.random.randn(*shape), dims=dims)
            with warnings.catch_warnings():
                warnings.filterwarnings('ignore', r'\W*Panel is deprecated')
                roundtripped = DataArray(da.to_pandas()).drop(dims)
            assert_identical(da, roundtripped)

        with raises_regex(ValueError, 'cannot convert'):
            DataArray(np.random.randn(1, 2, 3, 4, 5)).to_pandas()

    def test_to_dataframe(self):
        # regression test for #260
        arr = DataArray(np.random.randn(3, 4),
                        [('B', [1, 2, 3]), ('A', list('cdef'))], name='foo')
        expected = arr.to_series()
        actual = arr.to_dataframe()['foo']
        assert_array_equal(expected.values, actual.values)
        assert_array_equal(expected.name, actual.name)
        assert_array_equal(expected.index.values, actual.index.values)

        # regression test for coords with different dimensions
        arr.coords['C'] = ('B', [-1, -2, -3])
        expected = arr.to_series().to_frame()
        expected['C'] = [-1] * 4 + [-2] * 4 + [-3] * 4
        expected = expected[['C', 'foo']]
        actual = arr.to_dataframe()
        assert_array_equal(expected.values, actual.values)
        assert_array_equal(expected.columns.values, actual.columns.values)
        assert_array_equal(expected.index.values, actual.index.values)

        arr.name = None  # unnamed
        with raises_regex(ValueError, 'unnamed'):
            arr.to_dataframe()

    def test_to_pandas_name_matches_coordinate(self):
        # coordinate with same name as array
        arr = DataArray([1, 2, 3], dims='x', name='x')
        series = arr.to_series()
        assert_array_equal([1, 2, 3], series.values)
        assert_array_equal([0, 1, 2], series.index.values)
        assert 'x' == series.name
        assert 'x' == series.index.name

        frame = arr.to_dataframe()
        expected = series.to_frame()
        assert expected.equals(frame)

    def test_to_and_from_series(self):
        expected = self.dv.to_dataframe()['foo']
        actual = self.dv.to_series()
        assert_array_equal(expected.values, actual.values)
        assert_array_equal(expected.index.values, actual.index.values)
        assert 'foo' == actual.name
        # test roundtrip
        assert_identical(
            self.dv,
            DataArray.from_series(actual).drop(['x', 'y']))
        # test name is None
        actual.name = None
        expected_da = self.dv.rename(None)
        assert_identical(
            expected_da,
            DataArray.from_series(actual).drop(['x', 'y']))

    def test_series_categorical_index(self):
        # regression test for GH700
        if not hasattr(pd, 'CategoricalIndex'):
            pytest.skip('requires pandas with CategoricalIndex')

        s = pd.Series(np.arange(5), index=pd.CategoricalIndex(list('aabbc')))
        arr = DataArray(s)
        assert "'a'" in repr(arr)  # should not error

    def test_to_and_from_dict(self):
        array = DataArray(np.random.randn(2, 3), {'x': ['a', 'b']}, ['x', 'y'],
                          name='foo')
        expected = {'name': 'foo',
                    'dims': ('x', 'y'),
                    'data': array.values.tolist(),
                    'attrs': {},
                    'coords': {'x': {'dims': ('x',),
                                     'data': ['a', 'b'],
                                     'attrs': {}}}}
        actual = array.to_dict()

        # check that they are identical
        assert expected == actual

        # check roundtrip
        assert_identical(array, DataArray.from_dict(actual))

        # a more bare bones representation still roundtrips
        d = {'name': 'foo',
             'dims': ('x', 'y'),
             'data': array.values.tolist(),
             'coords': {'x': {'dims': 'x', 'data': ['a', 'b']}}}
        assert_identical(array, DataArray.from_dict(d))

        # and the most bare bones representation still roundtrips
        d = {'name': 'foo', 'dims': ('x', 'y'), 'data': array.values}
        assert_identical(array.drop('x'), DataArray.from_dict(d))

        # missing a dims in the coords
        d = {'dims': ('x', 'y'),
             'data': array.values,
             'coords': {'x': {'data': ['a', 'b']}}}
        with raises_regex(
                ValueError,
                "cannot convert dict when coords are missing the key 'dims'"):
            DataArray.from_dict(d)

        # this one is missing some necessary information
        d = {'dims': ('t')}
        with raises_regex(
                ValueError, "cannot convert dict without the key 'data'"):
            DataArray.from_dict(d)

    def test_to_and_from_dict_with_time_dim(self):
        x = np.random.randn(10, 3)
        t = pd.date_range('20130101', periods=10)
        lat = [77.7, 83.2, 76]
        da = DataArray(x, {'t': t, 'lat': lat}, dims=['t', 'lat'])
        roundtripped = DataArray.from_dict(da.to_dict())
        assert_identical(da, roundtripped)

    def test_to_and_from_dict_with_nan_nat(self):
        y = np.random.randn(10, 3)
        y[2] = np.nan
        t = pd.Series(pd.date_range('20130101', periods=10))
        t[2] = np.nan
        lat = [77.7, 83.2, 76]
        da = DataArray(y, {'t': t, 'lat': lat}, dims=['t', 'lat'])
        roundtripped = DataArray.from_dict(da.to_dict())
        assert_identical(da, roundtripped)

    def test_to_dict_with_numpy_attrs(self):
        # this doesn't need to roundtrip
        x = np.random.randn(10, 3)
        t = list('abcdefghij')
        lat = [77.7, 83.2, 76]
        attrs = {'created': np.float64(1998),
                 'coords': np.array([37, -110.1, 100]),
                 'maintainer': 'bar'}
        da = DataArray(x, {'t': t, 'lat': lat}, dims=['t', 'lat'],
                       attrs=attrs)
        expected_attrs = {'created': np.asscalar(attrs['created']),
                          'coords': attrs['coords'].tolist(),
                          'maintainer': 'bar'}
        actual = da.to_dict()

        # check that they are identical
        assert expected_attrs == actual['attrs']

    def test_to_masked_array(self):
        rs = np.random.RandomState(44)
        x = rs.random_sample(size=(10, 20))
        x_masked = np.ma.masked_where(x < 0.5, x)
        da = DataArray(x_masked)

        # Test round trip
        x_masked_2 = da.to_masked_array()
        da_2 = DataArray(x_masked_2)
        assert_array_equal(x_masked, x_masked_2)
        assert_equal(da, da_2)

        da_masked_array = da.to_masked_array(copy=True)
        assert isinstance(da_masked_array, np.ma.MaskedArray)
        # Test masks
        assert_array_equal(da_masked_array.mask, x_masked.mask)
        # Test that mask is unpacked correctly
        assert_array_equal(da.values, x_masked.filled(np.nan))
        # Test that the underlying data (including nans) hasn't changed
        assert_array_equal(da_masked_array, x_masked.filled(np.nan))

        # Test that copy=False gives access to values
        masked_array = da.to_masked_array(copy=False)
        masked_array[0, 0] = 10.
        assert masked_array[0, 0] == 10.
        assert da[0, 0].values == 10.
        assert masked_array.base is da.values
        assert isinstance(masked_array, np.ma.MaskedArray)

        # Test with some odd arrays
        for v in [4, np.nan, True, '4', 'four']:
            da = DataArray(v)
            ma = da.to_masked_array()
            assert isinstance(ma, np.ma.MaskedArray)

        # Fix GH issue 684 - masked arrays mask should be an array not a scalar
        N = 4
        v = range(N)
        da = DataArray(v)
        ma = da.to_masked_array()
        assert len(ma.mask) == N

    def test_to_and_from_cdms2_classic(self):
        """Classic with 1D axes"""
        pytest.importorskip('cdms2')

        original = DataArray(
            np.arange(6).reshape(2, 3),
            [('distance', [-2, 2], {'units': 'meters'}),
             ('time', pd.date_range('2000-01-01', periods=3))],
            name='foo', attrs={'baz': 123})
        expected_coords = [IndexVariable('distance', [-2, 2]),
                           IndexVariable('time', [0, 1, 2])]
        actual = original.to_cdms2()
        assert_array_equal(actual.asma(), original)
        assert actual.id == original.name
        assert tuple(actual.getAxisIds()) == original.dims
        for axis, coord in zip(actual.getAxisList(), expected_coords):
            assert axis.id == coord.name
            assert_array_equal(axis, coord.values)
        assert actual.baz == original.attrs['baz']

        component_times = actual.getAxis(1).asComponentTime()
        assert len(component_times) == 3
        assert str(component_times[0]) == '2000-1-1 0:0:0.0'

        roundtripped = DataArray.from_cdms2(actual)
        assert_identical(original, roundtripped)

        back = from_cdms2(actual)
        assert original.dims == back.dims
        assert original.coords.keys() == back.coords.keys()
        for coord_name in original.coords.keys():
            assert_array_equal(original.coords[coord_name],
                               back.coords[coord_name])

    def test_to_and_from_cdms2_sgrid(self):
        """Curvilinear (structured) grid

        The rectangular grid case is covered by the classic case
        """
        pytest.importorskip('cdms2')

        lonlat = np.mgrid[:3, :4]
        lon = DataArray(lonlat[1], dims=['y', 'x'], name='lon')
        lat = DataArray(lonlat[0], dims=['y', 'x'], name='lat')
        x = DataArray(np.arange(lon.shape[1]), dims=['x'], name='x')
        y = DataArray(np.arange(lon.shape[0]), dims=['y'], name='y')
        original = DataArray(lonlat.sum(axis=0), dims=['y', 'x'],
                             coords=OrderedDict(x=x, y=y, lon=lon, lat=lat),
                             name='sst')
        actual = original.to_cdms2()
        assert tuple(actual.getAxisIds()) == original.dims
        assert_array_equal(original.coords['lon'],
                           actual.getLongitude().asma())
        assert_array_equal(original.coords['lat'],
                           actual.getLatitude().asma())

        back = from_cdms2(actual)
        assert original.dims == back.dims
        assert set(original.coords.keys()) == set(back.coords.keys())
        assert_array_equal(original.coords['lat'], back.coords['lat'])
        assert_array_equal(original.coords['lon'], back.coords['lon'])

    def test_to_and_from_cdms2_ugrid(self):
        """Unstructured grid"""
        pytest.importorskip('cdms2')

        lon = DataArray(np.random.uniform(size=5), dims=['cell'], name='lon')
        lat = DataArray(np.random.uniform(size=5), dims=['cell'], name='lat')
        cell = DataArray(np.arange(5), dims=['cell'], name='cell')
        original = DataArray(np.arange(5), dims=['cell'],
                             coords={'lon': lon, 'lat': lat, 'cell': cell})
        actual = original.to_cdms2()
        assert tuple(actual.getAxisIds()) == original.dims
        assert_array_equal(original.coords['lon'],
                           actual.getLongitude().getValue())
        assert_array_equal(original.coords['lat'],
                           actual.getLatitude().getValue())

        back = from_cdms2(actual)
        assert set(original.dims) == set(back.dims)
        assert set(original.coords.keys()) == set(back.coords.keys())
        assert_array_equal(original.coords['lat'], back.coords['lat'])
        assert_array_equal(original.coords['lon'], back.coords['lon'])

    def test_to_dataset_whole(self):
        unnamed = DataArray([1, 2], dims='x')
        with raises_regex(ValueError, 'unable to convert unnamed'):
            unnamed.to_dataset()

        actual = unnamed.to_dataset(name='foo')
        expected = Dataset({'foo': ('x', [1, 2])})
        assert_identical(expected, actual)

        named = DataArray([1, 2], dims='x', name='foo')
        actual = named.to_dataset()
        expected = Dataset({'foo': ('x', [1, 2])})
        assert_identical(expected, actual)

        expected = Dataset({'bar': ('x', [1, 2])})
        with pytest.warns(FutureWarning):
            actual = named.to_dataset('bar')
        assert_identical(expected, actual)

    def test_to_dataset_split(self):
        array = DataArray([1, 2, 3], coords=[('x', list('abc'))],
                          attrs={'a': 1})
        expected = Dataset(OrderedDict([('a', 1), ('b', 2), ('c', 3)]),
                           attrs={'a': 1})
        actual = array.to_dataset('x')
        assert_identical(expected, actual)

        with pytest.raises(TypeError):
            array.to_dataset('x', name='foo')

        roundtripped = actual.to_array(dim='x')
        assert_identical(array, roundtripped)

        array = DataArray([1, 2, 3], dims='x')
        expected = Dataset(OrderedDict([(0, 1), (1, 2), (2, 3)]))
        actual = array.to_dataset('x')
        assert_identical(expected, actual)

    def test_to_dataset_retains_keys(self):

        # use dates as convenient non-str objects. Not a specific date test
        import datetime
        dates = [datetime.date(2000, 1, d) for d in range(1, 4)]

        array = DataArray([1, 2, 3], coords=[('x', dates)],
                          attrs={'a': 1})

        # convert to dateset and back again
        result = array.to_dataset('x').to_array(dim='x')

        assert_equal(array, result)

    def test__title_for_slice(self):
        array = DataArray(np.ones((4, 3, 2)), dims=['a', 'b', 'c'],
                          coords={'a': range(4), 'b': range(3), 'c': range(2)})
        assert '' == array._title_for_slice()
        assert 'c = 0' == array.isel(c=0)._title_for_slice()
        title = array.isel(b=1, c=0)._title_for_slice()
        assert 'b = 1, c = 0' == title or 'c = 0, b = 1' == title

        a2 = DataArray(np.ones((4, 1)), dims=['a', 'b'])
        assert '' == a2._title_for_slice()

    def test__title_for_slice_truncate(self):
        array = DataArray(np.ones((4)))
        array.coords['a'] = 'a' * 100
        array.coords['b'] = 'b' * 100

        nchar = 80
        title = array._title_for_slice(truncate=nchar)

        assert nchar == len(title)
        assert title.endswith('...')

    def test_dataarray_diff_n1(self):
        da = DataArray(np.random.randn(3, 4), dims=['x', 'y'])
        actual = da.diff('y')
        expected = DataArray(np.diff(da.values, axis=1), dims=['x', 'y'])
        assert_equal(expected, actual)

    def test_coordinate_diff(self):
        # regression test for GH634
        arr = DataArray(range(0, 20, 2), dims=['lon'], coords=[range(10)])
        lon = arr.coords['lon']
        expected = DataArray([1] * 9, dims=['lon'], coords=[range(1, 10)],
                             name='lon')
        actual = lon.diff('lon')
        assert_equal(expected, actual)

    @pytest.mark.parametrize('offset', [-5, 0, 1, 2])
    @pytest.mark.parametrize('fill_value, dtype',
                             [(2, int), (dtypes.NA, float)])
    def test_shift(self, offset, fill_value, dtype):
        arr = DataArray([1, 2, 3], dims='x')
        actual = arr.shift(x=1, fill_value=fill_value)
        if fill_value == dtypes.NA:
            # if we supply the default, we expect the missing value for a
            # float array
            fill_value = np.nan
        expected = DataArray([fill_value, 1, 2], dims='x')
        assert_identical(expected, actual)
        assert actual.dtype == dtype

        arr = DataArray([1, 2, 3], [('x', ['a', 'b', 'c'])])
        expected = DataArray(arr.to_pandas().shift(offset))
        actual = arr.shift(x=offset)
        assert_identical(expected, actual)

    def test_roll_coords(self):
        arr = DataArray([1, 2, 3], coords={'x': range(3)}, dims='x')
        actual = arr.roll(x=1, roll_coords=True)
        expected = DataArray([3, 1, 2], coords=[('x', [2, 0, 1])])
        assert_identical(expected, actual)

    def test_roll_no_coords(self):
        arr = DataArray([1, 2, 3], coords={'x': range(3)}, dims='x')
        actual = arr.roll(x=1, roll_coords=False)
        expected = DataArray([3, 1, 2], coords=[('x', [0, 1, 2])])
        assert_identical(expected, actual)

    def test_roll_coords_none(self):
        arr = DataArray([1, 2, 3], coords={'x': range(3)}, dims='x')

        with pytest.warns(FutureWarning):
            actual = arr.roll(x=1, roll_coords=None)

        expected = DataArray([3, 1, 2], coords=[('x', [2, 0, 1])])
        assert_identical(expected, actual)

    def test_copy_with_data(self):
        orig = DataArray(np.random.random(size=(2, 2)),
                         dims=('x', 'y'),
                         attrs={'attr1': 'value1'},
                         coords={'x': [4, 3]},
                         name='helloworld')
        new_data = np.arange(4).reshape(2, 2)
        actual = orig.copy(data=new_data)
        expected = orig.copy()
        expected.data = new_data
        assert_identical(expected, actual)

    def test_real_and_imag(self):
        array = DataArray(1 + 2j)
        assert_identical(array.real, DataArray(1))
        assert_identical(array.imag, DataArray(2))

    def test_setattr_raises(self):
        array = DataArray(0, coords={'scalar': 1}, attrs={'foo': 'bar'})
        with raises_regex(AttributeError, 'cannot set attr'):
            array.scalar = 2
        with raises_regex(AttributeError, 'cannot set attr'):
            array.foo = 2
        with raises_regex(AttributeError, 'cannot set attr'):
            array.other = 2

    def test_full_like(self):
        # For more thorough tests, see test_variable.py
        da = DataArray(np.random.random(size=(2, 2)),
                       dims=('x', 'y'),
                       attrs={'attr1': 'value1'},
                       coords={'x': [4, 3]},
                       name='helloworld')

        actual = full_like(da, 2)
        expect = da.copy(deep=True)
        expect.values = [[2.0, 2.0], [2.0, 2.0]]
        assert_identical(expect, actual)

        # override dtype
        actual = full_like(da, fill_value=True, dtype=bool)
        expect.values = [[True, True], [True, True]]
        assert expect.dtype == bool
        assert_identical(expect, actual)

    def test_dot(self):
        x = np.linspace(-3, 3, 6)
        y = np.linspace(-3, 3, 5)
        z = range(4)
        da_vals = np.arange(6 * 5 * 4).reshape((6, 5, 4))
        da = DataArray(da_vals, coords=[x, y, z], dims=['x', 'y', 'z'])

        dm_vals = range(4)
        dm = DataArray(dm_vals, coords=[z], dims=['z'])

        # nd dot 1d
        actual = da.dot(dm)
        expected_vals = np.tensordot(da_vals, dm_vals, [2, 0])
        expected = DataArray(expected_vals, coords=[x, y], dims=['x', 'y'])
        assert_equal(expected, actual)

        # all shared dims
        actual = da.dot(da)
        expected_vals = np.tensordot(da_vals, da_vals,
                                     axes=([0, 1, 2], [0, 1, 2]))
        expected = DataArray(expected_vals)
        assert_equal(expected, actual)

        # multiple shared dims
        dm_vals = np.arange(20 * 5 * 4).reshape((20, 5, 4))
        j = np.linspace(-3, 3, 20)
        dm = DataArray(dm_vals, coords=[j, y, z], dims=['j', 'y', 'z'])
        actual = da.dot(dm)
        expected_vals = np.tensordot(da_vals, dm_vals, axes=([1, 2], [1, 2]))
        expected = DataArray(expected_vals, coords=[x, j], dims=['x', 'j'])
        assert_equal(expected, actual)

        with pytest.raises(NotImplementedError):
            da.dot(dm.to_dataset(name='dm'))
        with pytest.raises(TypeError):
            da.dot(dm.values)

    def test_binary_op_join_setting(self):
        dim = 'x'
        align_type = "outer"
        coords_l, coords_r = [0, 1, 2], [1, 2, 3]
        missing_3 = xr.DataArray(coords_l, [(dim, coords_l)])
        missing_0 = xr.DataArray(coords_r, [(dim, coords_r)])
        with xr.set_options(arithmetic_join=align_type):
            actual = missing_0 + missing_3
        missing_0_aligned, missing_3_aligned = xr.align(missing_0,
                                                        missing_3,
                                                        join=align_type)
        expected = xr.DataArray([np.nan, 2, 4, np.nan], [(dim, [0, 1, 2, 3])])
        assert_equal(actual, expected)

    def test_combine_first(self):
        ar0 = DataArray([[0, 0], [0, 0]], [('x', ['a', 'b']), ('y', [-1, 0])])
        ar1 = DataArray([[1, 1], [1, 1]], [('x', ['b', 'c']), ('y', [0, 1])])
        ar2 = DataArray([2], [('x', ['d'])])

        actual = ar0.combine_first(ar1)
        expected = DataArray([[0, 0, np.nan], [0, 0, 1], [np.nan, 1, 1]],
                             [('x', ['a', 'b', 'c']), ('y', [-1, 0, 1])])
        assert_equal(actual, expected)

        actual = ar1.combine_first(ar0)
        expected = DataArray([[0, 0, np.nan], [0, 1, 1], [np.nan, 1, 1]],
                             [('x', ['a', 'b', 'c']), ('y', [-1, 0, 1])])
        assert_equal(actual, expected)

        actual = ar0.combine_first(ar2)
        expected = DataArray([[0, 0], [0, 0], [2, 2]],
                             [('x', ['a', 'b', 'd']), ('y', [-1, 0])])
        assert_equal(actual, expected)

    def test_sortby(self):
        da = DataArray([[1, 2], [3, 4], [5, 6]],
                       [('x', ['c', 'b', 'a']), ('y', [1, 0])])

        sorted1d = DataArray([[5, 6], [3, 4], [1, 2]],
                             [('x', ['a', 'b', 'c']), ('y', [1, 0])])

        sorted2d = DataArray([[6, 5], [4, 3], [2, 1]],
                             [('x', ['a', 'b', 'c']), ('y', [0, 1])])

        expected = sorted1d
        dax = DataArray([100, 99, 98], [('x', ['c', 'b', 'a'])])
        actual = da.sortby(dax)
        assert_equal(actual, expected)

        # test descending order sort
        actual = da.sortby(dax, ascending=False)
        assert_equal(actual, da)

        # test alignment (fills in nan for 'c')
        dax_short = DataArray([98, 97], [('x', ['b', 'a'])])
        actual = da.sortby(dax_short)
        assert_equal(actual, expected)

        # test multi-dim sort by 1D dataarray values
        expected = sorted2d
        dax = DataArray([100, 99, 98], [('x', ['c', 'b', 'a'])])
        day = DataArray([90, 80], [('y', [1, 0])])
        actual = da.sortby([day, dax])
        assert_equal(actual, expected)

        expected = sorted1d
        actual = da.sortby('x')
        assert_equal(actual, expected)

        expected = sorted2d
        actual = da.sortby(['x', 'y'])
        assert_equal(actual, expected)

    @requires_bottleneck
    def test_rank(self):
        # floats
        ar = DataArray([[3, 4, np.nan, 1]])
        expect_0 = DataArray([[1, 1, np.nan, 1]])
        expect_1 = DataArray([[2, 3, np.nan, 1]])
        assert_equal(ar.rank('dim_0'), expect_0)
        assert_equal(ar.rank('dim_1'), expect_1)
        # int
        x = DataArray([3, 2, 1])
        assert_equal(x.rank('dim_0'), x)
        # str
        y = DataArray(['c', 'b', 'a'])
        assert_equal(y.rank('dim_0'), x)

        x = DataArray([3.0, 1.0, np.nan, 2.0, 4.0], dims=('z',))
        y = DataArray([0.75, 0.25, np.nan, 0.5, 1.0], dims=('z',))
        assert_equal(y.rank('z', pct=True), y)


@pytest.fixture(params=[1])
def da(request):
    if request.param == 1:
        times = pd.date_range('2000-01-01', freq='1D', periods=21)
        values = np.random.random((3, 21, 4))
        da = DataArray(values, dims=('a', 'time', 'x'))
        da['time'] = times
        return da

    if request.param == 2:
        return DataArray(
            [0, np.nan, 1, 2, np.nan, 3, 4, 5, np.nan, 6, 7],
            dims='time')

    if request.param == 'repeating_ints':
        return DataArray(
            np.tile(np.arange(12), 5).reshape(5, 4, 3),
            coords={'x': list('abc'),
                    'y': list('defg')},
            dims=list('zyx')
        )


@pytest.fixture
def da_dask(seed=123):
    pytest.importorskip('dask.array')
    rs = np.random.RandomState(seed)
    times = pd.date_range('2000-01-01', freq='1D', periods=21)
    values = rs.normal(size=(1, 21, 1))
    da = DataArray(values, dims=('a', 'time', 'x')).chunk({'time': 7})
    da['time'] = times
    return da


@pytest.mark.parametrize('da', ('repeating_ints', ), indirect=True)
def test_isin(da):

    expected = DataArray(
        np.asarray([[0, 0, 0], [1, 0, 0]]),
        dims=list('yx'),
        coords={'x': list('abc'),
                'y': list('de')},
    ).astype('bool')

    result = da.isin([3]).sel(y=list('de'), z=0)
    assert_equal(result, expected)

    expected = DataArray(
        np.asarray([[0, 0, 1], [1, 0, 0]]),
        dims=list('yx'),
        coords={'x': list('abc'),
                'y': list('de')},
    ).astype('bool')
    result = da.isin([2, 3]).sel(y=list('de'), z=0)
    assert_equal(result, expected)


@pytest.mark.parametrize('da', (1, 2), indirect=True)
def test_rolling_iter(da):

    rolling_obj = da.rolling(time=7)
    with warnings.catch_warnings():
        warnings.filterwarnings('ignore', 'Mean of empty slice')
        rolling_obj_mean = rolling_obj.mean()

    assert len(rolling_obj.window_labels) == len(da['time'])
    assert_identical(rolling_obj.window_labels, da['time'])

    for i, (label, window_da) in enumerate(rolling_obj):
        assert label == da['time'].isel(time=i)

        with warnings.catch_warnings():
            warnings.filterwarnings('ignore', 'Mean of empty slice')
            actual = rolling_obj_mean.isel(time=i)
            expected = window_da.mean('time')

        # TODO add assert_allclose_with_nan, which compares nan position
        # as well as the closeness of the values.
        assert_array_equal(actual.isnull(), expected.isnull())
        if (~actual.isnull()).sum() > 0:
            np.allclose(actual.values[actual.values.nonzero()],
                        expected.values[expected.values.nonzero()])


def test_rolling_doc(da):
    rolling_obj = da.rolling(time=7)

    # argument substitution worked
    assert '`mean`' in rolling_obj.mean.__doc__


def test_rolling_properties(da):
    rolling_obj = da.rolling(time=4)

    assert rolling_obj.obj.get_axis_num('time') == 1

    # catching invalid args
    with pytest.raises(ValueError) as exception:
        da.rolling(time=7, x=2)
    assert 'exactly one dim/window should' in str(exception)
    with pytest.raises(ValueError) as exception:
        da.rolling(time=-2)
    assert 'window must be > 0' in str(exception)
    with pytest.raises(ValueError) as exception:
        da.rolling(time=2, min_periods=0)
    assert 'min_periods must be greater than zero' in str(exception)


@pytest.mark.parametrize('name', ('sum', 'mean', 'std', 'min', 'max',
                                  'median'))
@pytest.mark.parametrize('center', (True, False, None))
@pytest.mark.parametrize('min_periods', (1, None))
def test_rolling_wrapped_bottleneck(da, name, center, min_periods):
    bn = pytest.importorskip('bottleneck', minversion="1.1")

    # Test all bottleneck functions
    rolling_obj = da.rolling(time=7, min_periods=min_periods)

    func_name = 'move_{0}'.format(name)
    actual = getattr(rolling_obj, name)()
    expected = getattr(bn, func_name)(da.values, window=7, axis=1,
                                      min_count=min_periods)
    assert_array_equal(actual.values, expected)

    # Test center
    rolling_obj = da.rolling(time=7, center=center)
    actual = getattr(rolling_obj, name)()['time']
    assert_equal(actual, da['time'])


@pytest.mark.parametrize('name', ('mean', 'count'))
@pytest.mark.parametrize('center', (True, False, None))
@pytest.mark.parametrize('min_periods', (1, None))
@pytest.mark.parametrize('window', (7, 8))
def test_rolling_wrapped_dask(da_dask, name, center, min_periods, window):
    pytest.importorskip('dask.array')
    # dask version
    rolling_obj = da_dask.rolling(time=window, min_periods=min_periods,
                                  center=center)
    actual = getattr(rolling_obj, name)().load()
    # numpy version
    rolling_obj = da_dask.load().rolling(time=window, min_periods=min_periods,
                                         center=center)
    expected = getattr(rolling_obj, name)()

    # using all-close because rolling over ghost cells introduces some
    # precision errors
    assert_allclose(actual, expected)

    # with zero chunked array GH:2113
    rolling_obj = da_dask.chunk().rolling(time=window, min_periods=min_periods,
                                          center=center)
    actual = getattr(rolling_obj, name)().load()
    assert_allclose(actual, expected)


@pytest.mark.parametrize('center', (True, None))
def test_rolling_wrapped_dask_nochunk(center):
    # GH:2113
    pytest.importorskip('dask.array')

    da_day_clim = xr.DataArray(np.arange(1, 367),
                               coords=[np.arange(1, 367)], dims='dayofyear')
    expected = da_day_clim.rolling(dayofyear=31, center=center).mean()
    actual = da_day_clim.chunk().rolling(dayofyear=31, center=center).mean()
    assert_allclose(actual, expected)


@pytest.mark.parametrize('center', (True, False))
@pytest.mark.parametrize('min_periods', (None, 1, 2, 3))
@pytest.mark.parametrize('window', (1, 2, 3, 4))
def test_rolling_pandas_compat(center, window, min_periods):
    s = pd.Series(np.arange(10))
    da = DataArray.from_series(s)

    if min_periods is not None and window < min_periods:
        min_periods = window

    s_rolling = s.rolling(window, center=center,
                          min_periods=min_periods).mean()
    da_rolling = da.rolling(index=window, center=center,
                            min_periods=min_periods).mean()
    da_rolling_np = da.rolling(index=window, center=center,
                               min_periods=min_periods).reduce(np.nanmean)

    np.testing.assert_allclose(s_rolling.values, da_rolling.values)
    np.testing.assert_allclose(s_rolling.index, da_rolling['index'])
    np.testing.assert_allclose(s_rolling.values, da_rolling_np.values)
    np.testing.assert_allclose(s_rolling.index, da_rolling_np['index'])


@pytest.mark.parametrize('center', (True, False))
@pytest.mark.parametrize('window', (1, 2, 3, 4))
def test_rolling_construct(center, window):
    s = pd.Series(np.arange(10))
    da = DataArray.from_series(s)

    s_rolling = s.rolling(window, center=center, min_periods=1).mean()
    da_rolling = da.rolling(index=window, center=center, min_periods=1)

    da_rolling_mean = da_rolling.construct('window').mean('window')
    np.testing.assert_allclose(s_rolling.values, da_rolling_mean.values)
    np.testing.assert_allclose(s_rolling.index, da_rolling_mean['index'])

    # with stride
    da_rolling_mean = da_rolling.construct('window',
                                           stride=2).mean('window')
    np.testing.assert_allclose(s_rolling.values[::2], da_rolling_mean.values)
    np.testing.assert_allclose(s_rolling.index[::2], da_rolling_mean['index'])

    # with fill_value
    da_rolling_mean = da_rolling.construct(
        'window', stride=2, fill_value=0.0).mean('window')
    assert da_rolling_mean.isnull().sum() == 0
    assert (da_rolling_mean == 0.0).sum() >= 0


@pytest.mark.parametrize('da', (1, 2), indirect=True)
@pytest.mark.parametrize('center', (True, False))
@pytest.mark.parametrize('min_periods', (None, 1, 2, 3))
@pytest.mark.parametrize('window', (1, 2, 3, 4))
@pytest.mark.parametrize('name', ('sum', 'mean', 'std', 'max'))
def test_rolling_reduce(da, center, min_periods, window, name):

    if min_periods is not None and window < min_periods:
        min_periods = window

    if da.isnull().sum() > 1 and window == 1:
        # this causes all nan slices
        window = 2

    rolling_obj = da.rolling(time=window, center=center,
                             min_periods=min_periods)

    # add nan prefix to numpy methods to get similar # behavior as bottleneck
    actual = rolling_obj.reduce(getattr(np, 'nan%s' % name))
    expected = getattr(rolling_obj, name)()
    assert_allclose(actual, expected)
    assert actual.dims == expected.dims


@requires_np113
@pytest.mark.parametrize('center', (True, False))
@pytest.mark.parametrize('min_periods', (None, 1, 2, 3))
@pytest.mark.parametrize('window', (1, 2, 3, 4))
@pytest.mark.parametrize('name', ('sum', 'max'))
def test_rolling_reduce_nonnumeric(center, min_periods, window, name):
    da = DataArray([0, np.nan, 1, 2, np.nan, 3, 4, 5, np.nan, 6, 7],
                   dims='time').isnull()

    if min_periods is not None and window < min_periods:
        min_periods = window

    rolling_obj = da.rolling(time=window, center=center,
                             min_periods=min_periods)

    # add nan prefix to numpy methods to get similar behavior as bottleneck
    actual = rolling_obj.reduce(getattr(np, 'nan%s' % name))
    expected = getattr(rolling_obj, name)()
    assert_allclose(actual, expected)
    assert actual.dims == expected.dims


def test_rolling_count_correct():

    da = DataArray(
        [0, np.nan, 1, 2, np.nan, 3, 4, 5, np.nan, 6, 7], dims='time')

    kwargs = [{'time': 11, 'min_periods': 1},
              {'time': 11, 'min_periods': None},
              {'time': 7, 'min_periods': 2}]
    expecteds = [DataArray(
        [1, 1, 2, 3, 3, 4, 5, 6, 6, 7, 8], dims='time'),
        DataArray(
        [np.nan, np.nan, np.nan, np.nan, np.nan, np.nan,
         np.nan, np.nan, np.nan, np.nan, np.nan], dims='time'),
        DataArray(
        [np.nan, np.nan, 2, 3, 3, 4, 5, 5, 5, 5, 5], dims='time')]

    for kwarg, expected in zip(kwargs, expecteds):
        result = da.rolling(**kwarg).count()
        assert_equal(result, expected)

        result = da.to_dataset(name='var1').rolling(**kwarg).count()['var1']
        assert_equal(result, expected)


def test_raise_no_warning_for_nan_in_binary_ops():
    with pytest.warns(None) as record:
        xr.DataArray([1, 2, np.NaN]) > 0
    assert len(record) == 0


class TestIrisConversion(object):
    @requires_iris
    def test_to_and_from_iris(self):
        import iris
        import cf_units  # iris requirement

        # to iris
        coord_dict = OrderedDict()
        coord_dict['distance'] = ('distance', [-2, 2], {'units': 'meters'})
        coord_dict['time'] = ('time', pd.date_range('2000-01-01', periods=3))
        coord_dict['height'] = 10
        coord_dict['distance2'] = ('distance', [0, 1], {'foo': 'bar'})
        coord_dict['time2'] = (('distance', 'time'), [[0, 1, 2], [2, 3, 4]])

        original = DataArray(np.arange(6, dtype='float').reshape(2, 3),
                             coord_dict, name='Temperature',
                             attrs={'baz': 123, 'units': 'Kelvin',
                                    'standard_name': 'fire_temperature',
                                    'long_name': 'Fire Temperature'},
                             dims=('distance', 'time'))

        # Set a bad value to test the masking logic
        original.data[0, 2] = np.NaN

        original.attrs['cell_methods'] = \
            'height: mean (comment: A cell method)'
        actual = original.to_iris()
        assert_array_equal(actual.data, original.data)
        assert actual.var_name == original.name
        assert tuple(d.var_name for d in actual.dim_coords) == original.dims
        assert (actual.cell_methods == (iris.coords.CellMethod(
            method='mean',
            coords=('height', ),
            intervals=(),
            comments=('A cell method', )), ))

        for coord, orginal_key in zip((actual.coords()), original.coords):
            original_coord = original.coords[orginal_key]
            assert coord.var_name == original_coord.name
            assert_array_equal(
                coord.points, CFDatetimeCoder().encode(original_coord).values)
            assert (actual.coord_dims(coord) ==
                    original.get_axis_num(
                        original.coords[coord.var_name].dims))

        assert (actual.coord('distance2').attributes['foo'] ==
                original.coords['distance2'].attrs['foo'])
        assert (actual.coord('distance').units ==
                cf_units.Unit(original.coords['distance'].units))
        assert actual.attributes['baz'] == original.attrs['baz']
        assert actual.standard_name == original.attrs['standard_name']

        roundtripped = DataArray.from_iris(actual)
        assert_identical(original, roundtripped)

        actual.remove_coord('time')
        auto_time_dimension = DataArray.from_iris(actual)
        assert auto_time_dimension.dims == ('distance', 'dim_1')

    @requires_iris
    @requires_dask
    def test_to_and_from_iris_dask(self):
        import dask.array as da
        import iris
        import cf_units  # iris requirement

        coord_dict = OrderedDict()
        coord_dict['distance'] = ('distance', [-2, 2], {'units': 'meters'})
        coord_dict['time'] = ('time', pd.date_range('2000-01-01', periods=3))
        coord_dict['height'] = 10
        coord_dict['distance2'] = ('distance', [0, 1], {'foo': 'bar'})
        coord_dict['time2'] = (('distance', 'time'), [[0, 1, 2], [2, 3, 4]])

        original = DataArray(
            da.from_array(np.arange(-1, 5, dtype='float').reshape(2, 3), 3),
            coord_dict,
            name='Temperature',
            attrs=dict(baz=123, units='Kelvin',
                       standard_name='fire_temperature',
                       long_name='Fire Temperature'),
            dims=('distance', 'time'))

        # Set a bad value to test the masking logic
        original.data = da.ma.masked_less(original.data, 0)

        original.attrs['cell_methods'] = \
            'height: mean (comment: A cell method)'
        actual = original.to_iris()

        # Be careful not to trigger the loading of the iris data
        actual_data = actual.core_data() if \
            hasattr(actual, 'core_data') else actual.data
        assert_array_equal(actual_data, original.data)
        assert actual.var_name == original.name
        assert tuple(d.var_name for d in actual.dim_coords) == original.dims
        assert (actual.cell_methods == (iris.coords.CellMethod(
            method='mean',
            coords=('height', ),
            intervals=(),
            comments=('A cell method', )), ))

        for coord, orginal_key in zip((actual.coords()), original.coords):
            original_coord = original.coords[orginal_key]
            assert coord.var_name == original_coord.name
            assert_array_equal(
                coord.points, CFDatetimeCoder().encode(original_coord).values)
            assert (actual.coord_dims(coord) ==
                    original.get_axis_num(
                        original.coords[coord.var_name].dims))

        assert (actual.coord('distance2').attributes['foo'] == original.coords[
            'distance2'].attrs['foo'])
        assert (actual.coord('distance').units ==
                cf_units.Unit(original.coords['distance'].units))
        assert actual.attributes['baz'] == original.attrs['baz']
        assert actual.standard_name == original.attrs['standard_name']

        roundtripped = DataArray.from_iris(actual)
        assert_identical(original, roundtripped)

        # If the Iris version supports it then we should have a dask array
        # at each stage of the conversion
        if hasattr(actual, 'core_data'):
            assert isinstance(original.data, type(actual.core_data()))
            assert isinstance(original.data, type(roundtripped.data))

        actual.remove_coord('time')
        auto_time_dimension = DataArray.from_iris(actual)
        assert auto_time_dimension.dims == ('distance', 'dim_1')

    @requires_iris
    @pytest.mark.parametrize('var_name, std_name, long_name, name, attrs', [
        ('var_name', 'height', 'Height',
            'var_name', {'standard_name': 'height', 'long_name': 'Height'}),
        (None, 'height', 'Height',
            'height', {'standard_name': 'height', 'long_name': 'Height'}),
        (None, None, 'Height',
            'Height', {'long_name': 'Height'}),
        (None, None, None,
            None, {}),
    ])
    def test_da_name_from_cube(self, std_name, long_name, var_name, name,
                               attrs):
        from iris.cube import Cube

        data = []
        cube = Cube(data, var_name=var_name, standard_name=std_name,
                    long_name=long_name)
        result = xr.DataArray.from_iris(cube)
        expected = xr.DataArray(data, name=name, attrs=attrs)
        xr.testing.assert_identical(result, expected)

    @requires_iris
    @pytest.mark.parametrize('var_name, std_name, long_name, name, attrs', [
        ('var_name', 'height', 'Height',
            'var_name', {'standard_name': 'height', 'long_name': 'Height'}),
        (None, 'height', 'Height',
            'height', {'standard_name': 'height', 'long_name': 'Height'}),
        (None, None, 'Height',
            'Height', {'long_name': 'Height'}),
        (None, None, None,
            'unknown', {}),
    ])
    def test_da_coord_name_from_cube(self, std_name, long_name, var_name,
                                     name, attrs):
        from iris.cube import Cube
        from iris.coords import DimCoord

        latitude = DimCoord([-90, 0, 90], standard_name=std_name,
                            var_name=var_name, long_name=long_name)
        data = [0, 0, 0]
        cube = Cube(data, dim_coords_and_dims=[(latitude, 0)])
        result = xr.DataArray.from_iris(cube)
        expected = xr.DataArray(data, coords=[(name, [-90, 0, 90], attrs)])
        xr.testing.assert_identical(result, expected)

    @requires_iris
    def test_prevent_duplicate_coord_names(self):
        from iris.cube import Cube
        from iris.coords import DimCoord

        # Iris enforces unique coordinate names. Because we use a different
        # name resolution order a valid iris Cube with coords that have the
        # same var_name would lead to duplicate dimension names in the
        # DataArray
        longitude = DimCoord([0, 360], standard_name='longitude',
                             var_name='duplicate')
        latitude = DimCoord([-90, 0, 90], standard_name='latitude',
                            var_name='duplicate')
        data = [[0, 0, 0], [0, 0, 0]]
        cube = Cube(data, dim_coords_and_dims=[(longitude, 0), (latitude, 1)])
        with pytest.raises(ValueError):
            xr.DataArray.from_iris(cube)

    @requires_iris
    @pytest.mark.parametrize('coord_values', [
        ['IA', 'IL', 'IN'],  # non-numeric values
        [0, 2, 1],  # non-monotonic values
    ])
    def test_fallback_to_iris_AuxCoord(self, coord_values):
        from iris.cube import Cube
        from iris.coords import AuxCoord

        data = [0, 0, 0]
        da = xr.DataArray(data, coords=[coord_values], dims=['space'])
        result = xr.DataArray.to_iris(da)
        expected = Cube(data, aux_coords_and_dims=[
            (AuxCoord(coord_values, var_name='space'), 0)])
        assert result == expected