CLN: correct format string

Author: cpcloud

pandas/tools/plotting.py

@@ -98,9 +98,10 @@ def _get_standard_colors(num_colors=None, colormap=None, color_type='default',
     if color is None and colormap is not None:
         if isinstance(colormap, basestring):
             import matplotlib.cm as cm
+            cmap = colormap
             colormap = cm.get_cmap(colormap)
             if colormap is None:
-                raise ValueError("Colormap {0} is not recognized")
+                raise ValueError("Colormap {0} is not recognized".format(cmap))
         colors = map(colormap, np.linspace(0, 1, num=num_colors))
     elif color is not None:
         if colormap is not None: