clabel accepts callable as fmt kwarg; modified patch by Daniel Hyams

Author: efiring

CHANGELOG

@@ -1,3 +1,6 @@
+2011-02-20 clabel accepts a callable as an fmt kwarg; modified
+           patch by Daniel Hyams. - EF
+
 2011-02-18 scatter([], []) is now valid.  Also fixed issues
            with empty collections - BVR
 

examples/pylab_examples/contour_label_demo.py

@@ -9,6 +9,7 @@
 import numpy as np
 import matplotlib.cm as cm
 import matplotlib.mlab as mlab
+import matplotlib.ticker as ticker
 import matplotlib.pyplot as plt
 
 matplotlib.rcParams['xtick.direction'] = 'out'
@@ -68,7 +69,15 @@ def __repr__(self):
 # Label every other level using strings
 plt.clabel(CS,CS.levels[::2],inline=True,fmt=fmt,fontsize=10)
 
-##################################################
-# Show the hole thing
-##################################################
+# Use a Formatter
+
+plt.figure()
+
+CS = plt.contour(X, Y, 100**Z, locator=plt.LogLocator())
+fmt = ticker.LogFormatterMathtext()
+fmt.create_dummy_axis()
+plt.clabel(CS, CS.levels, fmt=fmt)
+plt.title("$100^Z$")
+
 plt.show()
+

lib/matplotlib/contour.py

@@ -95,7 +95,9 @@ def clabel(self, *args, **kwargs):
             a format string for the label. Default is '%1.3f'
             Alternatively, this can be a dictionary matching contour
             levels with arbitrary strings to use for each contour level
-            (i.e., fmt[level]=string)
+            (i.e., fmt[level]=string), or it can be any callable, such
+            as a :class:`~matplotlib.ticker.Formatter` instance, that
+            returns a string when called with a numeric contour level.
 
           *manual*:
             if *True*, contour labels will be placed manually using
@@ -326,6 +328,8 @@ def get_text(self, lev, fmt):
         else:
             if isinstance(fmt,dict):
                 return fmt[lev]
+            elif callable(fmt):
+                return fmt(lev)
             else:
                 return fmt%lev