Unpin Matplotlib and proj (#3762)

* unpin proj, move cartopy pin forward

* Explicit resolution of coastlines in tests - see SciTools/cartopy#1105.

* Removed gdal optional requirement.

* New target image for test_plot_custom_aggregation due to auto-sizing coastlines in SciTools/cartopy#1105. Twin commit: SciTools/test-iris-imagehash@9b4e50e.

* New acceptable images for various tests due to minor changes in Matplotlib 3.3. Twin commit: SciTools/test-iris-imagehash@3babde5.

* New target images for test plots affected by the gridline spacing change in SciTools/cartopy@2f5e568. Twin commit: SciTools/test-iris-imagehash@f071f2c.

* New acceptable images to allow for minute colormap range changes in Matplotlib 3.3. Twin commit: SciTools/test-iris-imagehash@9f4b04e.

* Improvement to quickplot time axis labelling and accompanying graphics test target changes. Twin commit: SciTools/test-iris-imagehash@3036a6f

* Made quickplot time axis label sensitive to MPL version (see matplotlib/matplotlib#15008).

* More target images following from 41b3b2a. Twin commit: SciTools/test-iris-imagehash@804ff68.

* More target images following from 27ea2f2. Twin commit: SciTools/test-iris-imagehash@f559a36.

* Mirroring _draw_2d_from_points() use of mpl date2num in _draw_2d_from_bounds(). Twin commit: SciTools/test-iris-imagehash@3c582dc.

* Re-instated all valid image targets for TestPlotCoordinatesGiven.test_tx.

* New target image for TestSimple.test_bounds following change to plot axis labelling. Twin commit: SciTools/test-iris-imagehash@770dc92.

* modify raster tests to handle new gdal behaviour

* modify raster tests to handle new gdal naming behaviour

* modify tests to reflect new PROJ behaviour

* modify parts of test_project to use Transverse Mercator

* revert test_project to use Robinson, add warning to docstring

* keep results consistent

Co-authored-by: Martin Yeo <martin.yeo@metoffice.gov.uk>

Author: stephenworsley

lib/iris/analysis/cartography.py

@@ -599,6 +599,12 @@ def project(cube, target_proj, nx=None, ny=None):
         on the statistics of the data e.g. the mean and standard deviation
         will not be preserved.
 
+    .. warning::
+
+        If the target projection is non-rectangular, e.g. Robinson, the target
+        grid may include points outside the boundary of the projection. The
+        latitude/longitude of such points may be unpredictable.
+
     """
     try:
         lon_coord, lat_coord = _get_lon_lat_coords(cube)

lib/iris/plot.py

@@ -441,6 +441,11 @@ def _draw_2d_from_bounds(draw_method_name, cube, *args, **kwargs):
                     values = np.arange(data.shape[data_dim] + 1) - 0.5
                 else:
                     values = coord.contiguous_bounds()
+                    values = _fixup_dates(coord, values)
+                    if values.dtype == np.dtype(object) and isinstance(
+                        values[0], datetime.datetime
+                    ):
+                        values = mpl_dates.date2num(values)
 
             plot_arrays.append(values)
 

lib/iris/quickplot.py

@@ -14,6 +14,7 @@
 """
 
 import cf_units
+from matplotlib import __version__ as mpl_version
 import matplotlib.pyplot as plt
 
 import iris.config
@@ -46,6 +47,13 @@ def _title(cube_or_coord, with_units):
 
             if _use_symbol(units):
                 units = units.symbol
+            if units.is_time_reference():
+                # iris.plot uses matplotlib.dates.date2num, which is fixed to the below unit.
+                if mpl_version >= "3.3":
+                    days_since = "1970-01-01"
+                else:
+                    days_since = "0001-01-01"
+                units = "days since {}".format(days_since)
             title += " / {}".format(units)
 
     return title

lib/iris/tests/experimental/test_raster.py

@@ -77,6 +77,10 @@ def _check_tiff_export(self, masked, inverted=False):
             339,
             33550,
             33922,
+            42113,
+            # Don't add a check entry for this, as coding changed between gdal
+            # version 1 and 2.
+            # tif_header_entries[42113] = (u'1e+20',)
         ]
         tif_header_entries = {
             256: (160,),
@@ -130,12 +134,6 @@ def _check_tiff_export(self, masked, inverted=False):
             # Mask some of the data + expect a slightly different header...
             cube.data = np.ma.masked_where(cube.data <= 380, cube.data)
 
-            # There is an additional key..
-            tif_header_keys += [42113]
-            # Don't add a check entry for this, as coding changed between gdal
-            # version 1 and 2, *and* between Python2 and Python3.
-            # tif_header_entries[42113] = (u'1e+20',)
-
         if inverted:
             # Check with the latitude coordinate (and the corresponding
             # cube.data) inverted.

lib/iris/tests/integration/plot/test_plot_2d_coords.py

@@ -43,14 +43,14 @@ def test_2d_coord_bounds_platecarree(self):
         cube = simple_cube_w_2d_coords()[0, 0]
         ax = plt.axes(projection=ccrs.PlateCarree(central_longitude=180))
         qplt.pcolormesh(cube)
-        ax.coastlines(color="red")
+        ax.coastlines(resolution="110m", color="red")
         self.check_graphic()
 
     def test_2d_coord_bounds_northpolarstereo(self):
         cube = simple_cube_w_2d_coords()[0, 0]
         ax = plt.axes(projection=ccrs.NorthPolarStereo())
         qplt.pcolormesh(cube)
-        ax.coastlines(color="red")
+        ax.coastlines(resolution="110m", color="red")
         self.check_graphic()
 
 
@@ -71,7 +71,7 @@ def test_2d_coords_contour(self):
         cube.add_aux_coord(co_x, (0, 1))
         ax = plt.axes(projection=ccrs.PlateCarree())
         qplt.contourf(cube)
-        ax.coastlines(color="red")
+        ax.coastlines(resolution="110m", color="red")
         ax.gridlines(draw_labels=True)
         ax.set_extent((0, 180, 0, 90))
         self.check_graphic()

lib/iris/tests/integration/plot/test_vector_plots.py

@@ -121,7 +121,7 @@ def test_2d_plain_latlon(self):
         self.plot(
             "latlon_2d", u_cube, v_cube, coords=("longitude", "latitude")
         )
-        ax.coastlines(color="red")
+        ax.coastlines(resolution="110m", color="red")
         ax.set_global()
         self.check_graphic()
 
@@ -132,7 +132,7 @@ def test_2d_plain_latlon_on_polar_map(self):
         self.plot(
             "latlon_2d_polar", u_cube, v_cube, coords=("longitude", "latitude")
         )
-        ax.coastlines(color="red")
+        ax.coastlines(resolution="110m", color="red")
         self.check_graphic()
 
     def test_2d_rotated_latlon(self):
@@ -142,7 +142,7 @@ def test_2d_rotated_latlon(self):
         self.plot(
             "2d_rotated", u_cube, v_cube, coords=("longitude", "latitude")
         )
-        ax.coastlines(color="red")
+        ax.coastlines(resolution="110m", color="red")
         ax.set_global()
         self.check_graphic()