Allow pandas.Series inputs to fig.histogram and pygmt.info (#1329)

Let 1D pandas.Series inputs work properly by modifying
the virtualfile_from_data function. Also added two tests
in test_histogram.py and test_info.py to ensure this works.

Author: weiji14

pygmt/clib/session.py

@@ -1449,9 +1449,11 @@ def virtualfile_from_data(
                 _data.extend(extra_arrays)
         elif kind == "matrix":  # turn 2D arrays into list of vectors
             try:
+                # pandas.Series will be handled below like a 1d numpy ndarray
+                assert not hasattr(data, "to_frame")
                 # pandas.DataFrame and xarray.Dataset types
                 _data = [array for _, array in data.items()]
-            except AttributeError:
+            except (AttributeError, AssertionError):
                 try:
                     # Just use virtualfile_from_matrix for 2D numpy.ndarray
                     # which are signed integer (i), unsigned integer (u) or
@@ -1460,7 +1462,7 @@ def virtualfile_from_data(
                     _virtualfile_from = self.virtualfile_from_matrix
                     _data = (data,)
                 except (AssertionError, AttributeError):
-                    # Python lists, tuples, and numpy ndarray types
+                    # Python list, tuple, numpy ndarray and pandas.Series types
                     _data = np.atleast_2d(np.asanyarray(data).T)
 
         # Finally create the virtualfile from the data, to be passed into GMT

pygmt/tests/test_histogram.py

@@ -2,22 +2,24 @@
 """
 Tests histogram.
 """
+import pandas as pd
 import pytest
 from pygmt import Figure
 
 
-@pytest.fixture(scope="module")
-def table():
+@pytest.fixture(scope="module", name="table", params=[list, pd.Series])
+def fixture_table(request):
     """
     Returns a list of integers to be used in the histogram.
     """
-    return [1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 4, 5, 6, 7, 8, 8, 8, 8, 8, 8]
+    data = [1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 4, 5, 6, 7, 8, 8, 8, 8, 8, 8]
+    return request.param(data)
 
 
-@pytest.mark.mpl_image_compare
+@pytest.mark.mpl_image_compare(filename="test_histogram.png")
 def test_histogram(table):
     """
-    Tests plotting a histogram using a list of integers.
+    Tests plotting a histogram using a sequence of integers from a table.
     """
     fig = Figure()
     fig.histogram(

pygmt/tests/test_info.py

@@ -38,6 +38,15 @@ def test_info_2d_list():
     assert output == expected_output
 
 
+def test_info_series():
+    """
+    Make sure info works on a pandas.Series input.
+    """
+    output = info(pd.Series(data=[0, 4, 2, 8, 6]))
+    expected_output = "<vector memory>: N = 5 <0/8>\n"
+    assert output == expected_output
+
+
 def test_info_dataframe():
     """
     Make sure info works on pandas.DataFrame inputs.