Revert cmap fix

doc/whats-new.rst

@@ -75,8 +75,6 @@ Bug fixes
   By `Mayeul d'Avezac <https://github.com/mdavezac>`_.
 - Return correct count for scalar datetime64 arrays (:issue:`2770`)
   By `Dan Nowacki <https://github.com/dnowacki-usgs>`_.
-- Fix facetgrid colormap bug when ``extend=True``. (:issue:`2932`)
-  By `Deepak Cherian <https://github.com/dcherian`_.
 - A deep copy deep-copies the coords (:issue:`1463`)
   By `Martin Pletcher <https://github.com/pletchm>`_.
 - Increased support for `missing_value` (:issue:`2871`)

xarray/plot/utils.py

@@ -264,8 +264,7 @@ def _determine_cmap_params(plot_data, vmin=None, vmax=None, cmap=None,
     if extend is None:
         extend = _determine_extend(calc_data, vmin, vmax)
 
-    if ((levels is not None or isinstance(norm, mpl.colors.BoundaryNorm))
-            and (not isinstance(cmap, mpl.colors.Colormap))):
+    if levels is not None or isinstance(norm, mpl.colors.BoundaryNorm):
         cmap, newnorm = _build_discrete_cmap(cmap, levels, extend, filled)
         norm = newnorm if norm is None else norm
 

xarray/tests/test_plot.py

@@ -8,6 +8,7 @@
 import xarray as xr
 import xarray.plot as xplt
 from xarray import DataArray
+from xarray.coding.times import _import_cftime
 from xarray.plot.plot import _infer_interval_breaks
 from xarray.plot.utils import (
     _build_discrete_cmap, _color_palette, _determine_cmap_params,
@@ -537,25 +538,6 @@ def test_cmap_sequential_option(self):
             cmap_params = _determine_cmap_params(self.data)
             assert cmap_params['cmap'] == 'magma'
 
-    def test_do_nothing_if_provided_cmap(self):
-        cmap_list = [
-            mpl.colors.LinearSegmentedColormap.from_list('name', ['r', 'g']),
-            mpl.colors.ListedColormap(['r', 'g', 'b'])
-        ]
-
-        # can't parametrize with mpl objects when mpl is absent
-        for cmap in cmap_list:
-            cmap_params = _determine_cmap_params(self.data,
-                                                 cmap=cmap,
-                                                 levels=7)
-            assert cmap_params['cmap'] is cmap
-
-    def test_do_something_if_provided_str_cmap(self):
-        cmap = 'RdBu_r'
-        cmap_params = _determine_cmap_params(self.data, cmap=cmap, levels=7)
-        assert cmap_params['cmap'] is not cmap
-        assert isinstance(cmap_params['cmap'], mpl.colors.ListedColormap)
-
     def test_cmap_sequential_explicit_option(self):
         with xr.set_options(cmap_sequential=mpl.cm.magma):
             cmap_params = _determine_cmap_params(self.data)
@@ -775,13 +757,14 @@ def test_discrete_colormap_list_of_levels(self):
 
     @pytest.mark.slow
     def test_discrete_colormap_int_levels(self):
-        for extend, levels, vmin, vmax in [('neither', 7, None, None),
-                                           ('neither', 7, None, 20),
-                                           ('both', 7, 4, 8),
-                                           ('min', 10, 4, 15)]:
+        for extend, levels, vmin, vmax, cmap in [
+                ('neither', 7, None, None, None),
+                ('neither', 7, None, 20, mpl.cm.RdBu),
+                ('both', 7, 4, 8, None),
+                ('min', 10, 4, 15, None)]:
             for kind in ['imshow', 'pcolormesh', 'contourf', 'contour']:
                 primitive = getattr(self.darray.plot, kind)(
-                    levels=levels, vmin=vmin, vmax=vmax)
+                    levels=levels, vmin=vmin, vmax=vmax, cmap=cmap)
                 assert levels >= \
                     len(primitive.norm.boundaries) - 1
                 if vmax is None: