fix an issue when *c* == 'none'

afvincent · afvincent · commit ee7a85433391 · 2018-06-06T20:56:42.000-07:00
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -3930,7 +3930,7 @@ def scatter(self, x, y, s=None, c=None, marker=None, cmap=None, norm=None,
 
         # Convenience vars to track shape mismatch *and* conversion failures.
         valid_shape = True  # will be put to the test!
-        n_elem = 0  # used only for (some) exceptions
+        n_elem = -1  # used only for (some) exceptions
 
         if c_none or co is not None:
             c_array = None
@@ -3960,8 +3960,9 @@ def scatter(self, x, y, s=None, c=None, marker=None, cmap=None, norm=None,
             try:  # Then is 'c' acceptable as PathCollection facecolors?
                 colors = mcolors.to_rgba_array(c)
                 n_elem = colors.shape[0]
-                if colors.shape[0] not in (1, x.size, y.size):
+                if colors.shape[0] not in (0, 1, x.size, y.size):
                     # NB: remember that a single color is also acceptable.
+                    # Besides *colors* will be an empty array if c == 'none'.
                     valid_shape = False
                     raise ValueError
             except ValueError:
