BUG : fix #3805

tacaswell · tacaswell · commit e9f0839352b7 · 2014-11-16T14:14:32.000-05:00
Enusure that norm.v{min,max} are not `None` before expanding
them to ensure that 0 &lt; vmax-vmin.
diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
@@ -653,12 +653,14 @@ def _process_values(self, b=None):
             self._values = v
             return
         else:
-            self.norm.vmin, self.norm.vmax = mtrans.nonsingular(self.norm.vmin,
-                                                                self.norm.vmax,
-                                                                expander=0.1)
             if not self.norm.scaled():
                 self.norm.vmin = 0
                 self.norm.vmax = 1
+
+            self.norm.vmin, self.norm.vmax = mtrans.nonsingular(self.norm.vmin,
+                                                                self.norm.vmax,
+                                                                expander=0.1)
+
             b = self.norm.inverse(self._uniform_y(self.cmap.N + 1))
             if self._extend_lower():
                 b[0] = b[0] - 1
