Merge branch 'v1.1.x'

efiring · efiring · commit f4a0719a36a4 · 2012-01-01T00:01:24.000-10:00
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
@@ -1683,6 +1683,8 @@ def colormaps():
 def colorbar(mappable=None, cax=None, ax=None, **kw):
     if mappable is None:
         mappable = gci()
+        if mappable is None:
+            raise RuntimeError('You must first define an image, eg with imshow')
     if ax is None:
         ax = gca()
 
@@ -1733,6 +1735,9 @@ def set_cmap(cmap):
 
     if im is not None:
         im.set_cmap(cmap)
+    else:
+        raise RuntimeError('You must first define an image, eg with imshow')
+
     draw_if_interactive()
 
 
diff --git a/lib/mpl_toolkits/axes_grid1/colorbar.py b/lib/mpl_toolkits/axes_grid1/colorbar.py
@@ -544,9 +544,8 @@ def _add_solids(self, X, Y, C):
         del self.solids
         del self.dividers
 
-        col = self.ax.pcolor(*args, **kw)
-        col.set_antialiased(False) # This is to suppress artifacts. We
-                                   # may use pcolormesh instead.
+        col = self.ax.pcolormesh(*args, **kw)
+
         self.solids = col
         if self.drawedges:
             self.dividers = collections.LineCollection(self._edges(X,Y),
