matplotlib · efiring · May 7, 2016 · May 6, 2016 · May 6, 2016 · May 6, 2016
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/rcsetup.py b/lib/matplotlib/rcsetup.py
@@ -22,6 +22,8 @@
 import operator
 import os
 import warnings
+import re
+
 try:
     import collections.abc as abc
 except ImportError:
@@ -30,10 +32,11 @@
 from matplotlib.fontconfig_pattern import parse_fontconfig_pattern
 from matplotlib.colors import is_color_like
 
+
 # Don't let the original cycler collide with our validating cycler
 from cycler import Cycler, cycler as ccycler
 
-#interactive_bk = ['gtk', 'gtkagg', 'gtkcairo', 'qt4agg',
+# interactive_bk = ['gtk', 'gtkagg', 'gtkcairo', 'qt4agg',
 #                  'tkagg', 'wx', 'wxagg', 'cocoaagg', 'webagg']
 # The capitalized forms are needed for ipython at present; this may
 # change for later versions.
@@ -175,6 +178,7 @@ def validate_string_or_None(s):
     except ValueError:
         raise ValueError('Could not convert "%s" to string' % s)
 
+
 def validate_axisbelow(s):
     try:
         return validate_bool(s)
@@ -340,6 +344,22 @@ def validate_color_or_auto(s):
     return validate_color(s)
 
 
+def validate_color_for_prop_cycle(s):
+    # Special-case the N-th color cycle syntax, this obviously can not
+    # go in the color cycle.
+    if isinstance(s, bytes):
+        match = re.match(b'^C[0-9]$', s)
+        if match is not None:
+            raise ValueError('Can not put cycle reference ({cn!r}) in '
+                             'prop_cycler'.format(cn=s))
+    elif isinstance(s, six.text_type):
+        match = re.match('^C[0-9]$', s)
+        if match is not None:
+            raise ValueError('Can not put cycle reference ({cn!r}) in '
+                             'prop_cycler'.format(cn=s))
+    return validate_color(s)
+
+
 def validate_color(s):
     'return a valid color arg'
     try:
@@ -649,7 +669,7 @@ def validate_hatch(s):
     characters: ``\\ / | - + * . x o O``.
 
     """
-    if not isinstance(s, six.text_type):
+    if not isinstance(s, six.string_types):
         raise ValueError("Hatch pattern must be a string")
     unique_chars = set(s)
     unknown = (unique_chars -
@@ -661,7 +681,8 @@ def validate_hatch(s):
 
 
 _prop_validators = {
-        'color': validate_colorlist,
+        'color': _listify_validator(validate_color_for_prop_cycle,
+                                    allow_stringlist=True),
         'linewidth': validate_floatlist,
         'linestyle': validate_stringlist,
         'facecolor': validate_colorlist,
@@ -818,6 +839,9 @@ def validate_cycler(s):
         norm_prop = _prop_aliases.get(prop, prop)
         cycler_inst.change_key(prop, norm_prop)
 
+    for key, vals in cycler_inst.by_key().items():
+        _prop_validators[key](vals)
+
     return cycler_inst
 
 

diff --git a/lib/matplotlib/tests/baseline_images/test_cycles/property_collision_plot.png b/lib/matplotlib/tests/baseline_images/test_cycles/property_collision_plot.png
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)
diff --git a/lib/matplotlib/tests/test_cycles.py b/lib/matplotlib/tests/test_cycles.py
@@ -129,7 +129,7 @@ def test_property_collision_plot():
     fig, ax = plt.subplots()
     ax.set_prop_cycle('linewidth', [2, 4])
     for c in range(1, 4):
-        ax.plot(np.arange(10), c * np.arange(10), lw=0.1)
+        ax.plot(np.arange(10), c * np.arange(10), lw=0.1, color='k')
     ax.plot(np.arange(10), 4 * np.arange(10))
     ax.plot(np.arange(10), 5 * np.arange(10))
 

diff --git a/lib/matplotlib/tests/test_rcparams.py b/lib/matplotlib/tests/test_rcparams.py
@@ -348,6 +348,7 @@ def test_validators():
                   ('cycler(c=[1, 2, 3])', ValueError),  # invalid values
                   ("cycler(lw=['a', 'b', 'c'])", ValueError),  # invalid values
                   (cycler('waka', [1, 3, 5]), ValueError),  # not a property
+                  (cycler('color', ['C1', 'r', 'g']), ValueError)  # no CN
                  )
         },
         {'validator': validate_hatch,