Merge pull request #6517 from anntzer/fix-string-gray-conversion

zblz · tacaswell · commit 1e35d8d96239 · 2016-06-03T14:02:24.000-04:00
Fix conversion of string grays with alpha.
diff --git a/lib/matplotlib/colors.py b/lib/matplotlib/colors.py
@@ -146,11 +146,12 @@ def _to_rgba_no_colorcycle(c, alpha=None):
     If `alpha` is not `None`, it forces the alpha value.
     """
     orig_c = c
-    if isinstance(c, six.string_types) and c.lower() == "none":
-        return (0., 0., 0., 0.)
     if isinstance(c, six.string_types):
+        if c.lower() == "none":
+            return (0., 0., 0., 0.)
         # Named color.
         try:
+            # This may turn c into a non-string, so we check again below.
             c = _colors_full_map[c.lower()]
         except KeyError:
             pass
@@ -161,7 +162,6 @@ def _to_rgba_no_colorcycle(c, alpha=None):
             return (tuple(int(n, 16) / 255
                           for n in [c[1:3], c[3:5], c[5:7]])
                     + (alpha if alpha is not None else 1.,))
-    if isinstance(c, six.string_types):
         # hex color with alpha.
         match = re.match(r"\A#[a-fA-F0-9]{8}\Z", c)
         if match:
@@ -170,10 +170,9 @@ def _to_rgba_no_colorcycle(c, alpha=None):
             if alpha is not None:
                 color[-1] = alpha
             return tuple(color)
-    if isinstance(c, six.string_types):
         # string gray.
         try:
-            return (float(c),) * 3 + (1.,)
+            return (float(c),) * 3 + (alpha if alpha is not None else 1.,)
         except ValueError:
             pass
         raise ValueError("Invalid RGBA argument: {!r}".format(orig_c))
diff --git a/lib/matplotlib/tests/test_colors.py b/lib/matplotlib/tests/test_colors.py
@@ -608,6 +608,7 @@ def test_conversions():
     assert_array_equal(mcolors.to_rgba_array("none"), np.zeros((0, 4)))
     # alpha is properly set.
     assert_equal(mcolors.to_rgba((1, 1, 1), .5), (1, 1, 1, .5))
+    assert_equal(mcolors.to_rgba(".1", .5), (.1, .1, .1, .5))
     # builtin round differs between py2 and py3.
     assert_equal(mcolors.to_hex((.7, .7, .7)), "#b2b2b2")
     # hex roundtrip.
