FIX: do not directly cache 'CN' color values

tacaswell · tacaswell · commit 6db04da9abce · 2016-05-06T15:46:00.000-04:00
diff --git a/lib/matplotlib/colors.py b/lib/matplotlib/colors.py
@@ -54,11 +54,11 @@
 """
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
-
+import re
 from matplotlib.externals import six
 from matplotlib.externals.six.moves import zip
 import warnings
-import re
+
 import numpy as np
 from numpy import ma
 import matplotlib.cbook as cbook
@@ -194,14 +194,17 @@ def to_rgb(self, arg):
                 raise ValueError(
                     'to_rgb: arg "%s" is unhashable even inside a tuple'
                     % (str(arg),))
-
         try:
             if cbook.is_string_like(arg):
                 argl = arg.lower()
                 color = self.colors.get(argl, None)
                 if color is None:
                     try:
                         argl = self._parse_nth_color(arg)
+                        # in this case we do not want to cache in case
+                        # the rcparam changes, recurse with the actual color
+                        # value
+                        return self.to_rgb(argl)
                     except ValueError:
                         pass
                     for cmapping in self.CN_LOOKUPS:
@@ -215,7 +218,7 @@ def to_rgb(self, arg):
                         if fl < 0 or fl > 1:
                             raise ValueError(
                                 'gray (string) must be in range 0-1')
-                        color = (fl,)*3
+                        color = (fl,) * 3
             elif cbook.iterable(arg):
                 if len(arg) > 4 or len(arg) < 3:
                     raise ValueError(
@@ -228,7 +231,6 @@ def to_rgb(self, arg):
             else:
                 raise ValueError(
                     'cannot convert argument to rgb sequence')
-
             self.cache[arg] = color
 
         except (KeyError, ValueError, TypeError) as exc:
diff --git a/lib/matplotlib/tests/test_colors.py b/lib/matplotlib/tests/test_colors.py
@@ -17,6 +17,8 @@
 from numpy.testing.utils import assert_array_equal, assert_array_almost_equal
 from nose.plugins.skip import SkipTest
 
+from cycler import cycler
+import matplotlib
 import matplotlib.colors as mcolors
 import matplotlib.cm as cm
 import matplotlib.cbook as cbook
@@ -596,6 +598,23 @@ def test_pandas_iterable():
     assert_sequence_equal(cm1.colors, cm2.colors)
 
 
+@cleanup
+def test_cn():
+    matplotlib.rcParams['axes.prop_cycle'] = cycler('color',
+                                                    ['blue', 'r'])
+    x11_blue = mcolors.rgb2hex(mcolors.colorConverter.to_rgb('C0'))
+    assert x11_blue == '#0000ff'
+    red = mcolors.rgb2hex(mcolors.colorConverter.to_rgb('C1'))
+    assert red == '#ff0000'
+
+    matplotlib.rcParams['axes.prop_cycle'] = cycler('color',
+                                                    ['XKCDblue', 'r'])
+    XKCD_blue = mcolors.rgb2hex(mcolors.colorConverter.to_rgb('C0'))
+    assert XKCD_blue == '#0343df'
+    red = mcolors.rgb2hex(mcolors.colorConverter.to_rgb('C1'))
+    assert red == '#ff0000'
+
+
 if __name__ == '__main__':
     import nose
     nose.runmodule(argv=['-s', '--with-doctest'], exit=False)
