SF.net SVN: matplotlib:[6256] trunk/matplotlib/lib/matplotlib/colors.py

[<ef...@us...>]

Revision: 6256
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=6256&view=rev
Author:   efiring
Date:     2008-10-18 19:51:22 +0000 (Sat, 18 Oct 2008)

Log Message:
-----------
Clip floating point values before conversion to integer; thanks to Tony Yu.

Modified Paths:
--------------
    trunk/matplotlib/lib/matplotlib/colors.py

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2008-10-18 17:47:28 UTC (rev 6255)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2008-10-18 19:51:22 UTC (rev 6256)
@@ -455,7 +455,10 @@
             mask_bad = ma.getmask(xma)
         if xa.dtype.char in np.typecodes['Float']:
             np.putmask(xa, xa==1.0, 0.9999999) #Treat 1.0 as slightly less than 1.
-            xa = (xa * self.N).astype(int)
+            # The following clip is fast, and prevents possible
+            # conversion of large positive values to negative integers.
+            np.clip(xa * self.N, -1, self.N, out=xa)
+            xa = xa.astype(int)
         # Set the over-range indices before the under-range;
         # otherwise the under-range values get converted to over-range.
         np.putmask(xa, xa>self.N-1, self._i_over)


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