updated fix for #8818

zhangeugenia · zhangeugenia · commit fb2064061915 · 2018-03-22T01:12:43.000-04:00
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -55,6 +55,14 @@ def _plot_args_replacer(args, data):
         return ["y"]
     elif len(args) == 2:
         # this can be two cases: x,y or y,c
+        if (not args[1] in data and
+            not (hasattr(data, 'dtype') and
+                 hasattr(data.dtype, 'names') and
+                 data.dtype.names is not None and
+                 args[1] in data.dtype.names)):
+            # this is not in data, so just assume that it is something which
+            # will not get replaced (color spec or array like).
+            return ["y", "c"]
         # it's data, but could be a color code like 'ro' or 'b--'
         # -> warn the user in that case...
 
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -588,6 +588,7 @@ def test_structured_data():
     # support for stuctured data
     pts = np.array([(1, 1), (2, 2)], dtype=[("ones", float), ("twos", float)])
 
+    # this should not read second name as a format and raise ValueError
     fig, ax = plt.subplots(2)
     ax[0].plot("ones", "twos", data=pts)
     ax[1].plot("ones", "twos", "r", data=pts)
