Skip masking for empty x.

TrishGillett · TrishGillett · commit da16535a87bd · 2016-09-18T13:32:48.000-04:00
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -6149,12 +6149,13 @@ def _normalize_input(inp, ename='input'):
 
         # Combine the masks from x[i] and w[i] (if applicable) into a single
         # mask and apply it to both.
-        for i in range(len(x)):
-            mask_i = x[i].mask
-            if w[i] is not None:
-                mask_i = mask_i & w[i].mask
-                w[i] = np.ma.masked_array(w[i], mask=mask_i).compressed()
-            x[i] = np.ma.masked_array(x[i], mask=mask_i).compressed()
+        if not input_empty:
+            for i in range(len(x)):
+                mask_i = x[i].mask
+                if w[i] is not None:
+                    mask_i = mask_i & w[i].mask
+                    w[i] = np.ma.masked_array(w[i], mask=mask_i).compressed()
+                x[i] = np.ma.masked_array(x[i], mask=mask_i).compressed()
 
         if color is None:
             color = [self._get_lines.get_next_color() for i in xrange(nx)]
