Thread: SF.net SVN: matplotlib:[5975] trunk/matplotlib/lib/matplotlib/colors.py

Revision: 5975
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=5975&view=rev
Author:   mdboom
Date:     2008-08-05 17:44:55 +0000 (Tue, 05 Aug 2008)

Log Message:
-----------
Fix Nx3 color array bug.

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2008-08-05 17:25:12 UTC (rev 5974)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2008-08-05 17:44:55 UTC (rev 5975)
@@ -337,11 +337,21 @@
             # If c is a list it must be maintained as the same list
             # with modified items so that items can be appended to
             # it. This is needed for examples/dynamic_collections.py.
-            if not isinstance(c, (list, np.ndarray)): # specific; don't need duck-typing
-                c = list(c)
+            if isinstance(c, np.ndarray):
+                if len(c.shape) != 2:
+                    raise ValueError("Color array must be two-dimensional")
+                if c.shape[1] != 4:
+                    output = np.zeros((c.shape[0], 4))
+                else:
+                    output = c
+            elif not isinstance(c, list):
+                output = list(c)
+            else:
+                output = c
+
             for i, cc in enumerate(c):
-                c[i] = self.to_rgba(cc, alpha)  # change in place
-            result = c
+                output[i] = self.to_rgba(cc, alpha)  # change in place
+            result = output
         return np.asarray(result, np.float_)
 
 colorConverter = ColorConverter()


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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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Revision: 6413
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=6413&view=rev
Author:   efiring
Date:     2008-11-18 21:37:25 +0000 (Tue, 18 Nov 2008)

Log Message:
-----------
Improved docstrings in colors.py

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2008-11-17 23:08:20 UTC (rev 6412)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2008-11-18 21:37:25 UTC (rev 6413)
@@ -1,10 +1,25 @@
 """
-A class for converting color arguments to RGB or RGBA
+A module for converting numbers or color arguments to *RGB* or *RGBA*
 
-This class instantiates a single instance colorConverter that is used
-to convert matlab color strings to RGB.  RGB is a tuple of float RGB
-values in the range 0-1.
+*RGB* and *RGBA* are sequences of, respectively, 3 or 4 floats in the
+range 0-1.
 
+This module includes functions and classes for color specification
+conversions, and for mapping numbers to colors in a 1-D array of
+colors called a colormap. Colormapping typically involves two steps:
+a data array is first mapped onto the range 0-1 using an instance
+of :class:`Normalize` or of a subclass; then this number in the 0-1
+range is mapped to a color using an instance of a subclass of
+:class:`Colormap`.  Two are provided here:
+:class:`LinearSegmentedColormap`, which is used to generate all
+the built-in colormap instances, but is also useful for making
+custom colormaps, and :class:`ListedColormap`, which is used for
+generating a custom colormap from a list of color specifications.
+
+The module also provides a single instance, *colorConverter*, of the
+:class:`ColorConverter` class providing methods for converting single
+color specifications or sequences of them to *RGB* or *RGBA*.
+
 Commands which take color arguments can use several formats to specify
 the colors.  For the basic builtin colors, you can use a single letter
 
@@ -193,6 +208,7 @@
         cnames[k] = v
 
 def is_color_like(c):
+    'Return *True* if *c* can be converted to *RGB*'
     try:
         colorConverter.to_rgb(c)
         return True
@@ -218,6 +234,15 @@
     return tuple([int(n, 16)/255.0 for n in (s[1:3], s[3:5], s[5:7])])
 
 class ColorConverter:
+    """
+    Provides methods for converting color specifications to *RGB* or *RGBA*
+
+    Caching is used for more efficient conversion upon repeated calls
+    with the same argument.
+
+    Ordinarily only the single instance instantiated in this module,
+    *colorConverter*, is needed.
+    """
     colors = {
         'b' : (0.0, 0.0, 1.0),
         'g' : (0.0, 0.5, 0.0),
@@ -526,18 +551,48 @@
 class LinearSegmentedColormap(Colormap):
     """Colormap objects based on lookup tables using linear segments.
 
-    The lookup transfer function is a simple linear function between
-    defined intensities. There is no limit to the number of segments
-    that may be defined. Though as the segment intervals start containing
-    fewer and fewer array locations, there will be inevitable quantization
-    errors
+    The lookup table is generated using linear interpolation for each
+    primary color, with the 0-1 domain divided into any number of
+    segments.
     """
     def __init__(self, name, segmentdata, N=256):
         """Create color map from linear mapping segments
 
         segmentdata argument is a dictionary with a red, green and blue
-        entries. Each entry should be a list of x, y0, y1 tuples.
+        entries. Each entry should be a list of *x*, *y0*, *y1* tuples,
+        forming rows in a table.
 
+        Example: suppose you want red to increase from 0 to 1 over
+        the bottom half, green to do the same over the middle half,
+        and blue over the top half.  Then you would use::
+
+            cdict = {'red':   [(0.0,  0.0, 0.0),
+                               (0.5,  1.0, 1.0),
+                               (1.0,  1.0, 1.0)],
+
+                     'green': [(0.0,  0.0, 0.0),
+                               (0.25, 0.0, 0.0),
+                               (0.75, 1.0, 1.0),
+                               (1.0,  1.0, 1.0)],
+
+                     'blue':  [(0.0,  0.0, 0.0),
+                               (0.5,  0.0, 0.0),
+                               (1.0,  1.0, 1.0)]}
+
+        Each row in the table for a given color is a sequence of
+        *x*, *y0*, *y1* tuples.  In each sequence, *x* must increase
+        monotonically from 0 to 1.  For any input value *z* falling
+        between *x[i]* and *x[i+1]*, the output value of a given color
+        will be linearly interpolated between *y1[i]* and *y0[i+1]*::
+
+            row i:   x  y0  y1
+                           /
+                          /
+            row i+1: x  y0  y1
+
+        Hence y0 in the first row and y1 in the last row are never used.
+
+
         .. seealso::
             :func:`makeMappingArray`
         """


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Revision: 6976
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=6976&view=rev
Author:   jswhit
Date:     2009-03-14 13:49:09 +0000 (Sat, 14 Mar 2009)

Log Message:
-----------
fix bug in hsv_to_rgb (returned rgb array wrong shape)

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2009-03-14 13:22:32 UTC (rev 6975)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2009-03-14 13:49:09 UTC (rev 6976)
@@ -951,7 +951,9 @@
     r[idx] = v[idx]; g[idx] = p[idx]; b[idx] = q[idx]
     idx = s == 0
     r[idx] = v[idx]; g[idx] = v[idx]; b[idx] = v[idx]
-    return np.array((r,g,b)).T
+    rgb = np.empty_like(hsv)
+    rgb[:,:,0]=r; rgb[:,:,1]=g; rgb[:,:,2]=b
+    return rgb
 
 class lightsource(object):
     """


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Revision: 6978
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=6978&view=rev
Author:   jswhit
Date:     2009-03-14 13:54:37 +0000 (Sat, 14 Mar 2009)

Log Message:
-----------
docstring fix for lightsource class

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2009-03-14 13:53:24 UTC (rev 6977)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2009-03-14 13:54:37 UTC (rev 6978)
@@ -959,7 +959,7 @@
     """
     Create a light source coming from the specified azimuth and elevation.
     Angles are in degrees, with the azimuth measured
-    clockwise from south and elevation up from the zero plane of the surface.
+    clockwise from north and elevation up from the zero plane of the surface.
     The :meth:`shade` is used to produce rgb values for a shaded relief image
     given a data array.
     """


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Revision: 7189
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=7189&view=rev
Author:   efiring
Date:     2009-06-06 21:35:36 +0000 (Sat, 06 Jun 2009)

Log Message:
-----------
Tweak John's change to handling of rgba arrays

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2009-06-06 18:21:51 UTC (rev 7188)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2009-06-06 21:35:36 UTC (rev 7189)
@@ -361,27 +361,35 @@
         then an empty array will be returned.  Same for an empty list.
         """
         try:
-            if c.lower() == 'none':
-                return np.zeros((0,4), dtype=np.float_)
+            nc = len(c)
+        except TypeError:
+            raise ValueError(
+                "Cannot convert argument type %s to rgba array" % type(c))
+        try:
+            if nc == 0 or c.lower() == 'none':
+                return np.zeros((0,4), dtype=np.float)
         except AttributeError:
             pass
-        if len(c) == 0:
-            return np.zeros((0,4), dtype=np.float_)
         try:
-            result = np.array([self.to_rgba(c, alpha)], dtype=np.float_)
+            # Single value? Put it in an array with a single row.
+            return np.array([self.to_rgba(c, alpha)], dtype=np.float)
         except ValueError:
             if isinstance(c, np.ndarray):
                 if c.ndim != 2 and c.dtype.kind not in 'SU':
                     raise ValueError("Color array must be two-dimensional")
-                if len(c.shape)==2 and c.shape[-1]==4:
+                if (c.ndim == 2 and c.shape[1] == 4 and c.dtype.kind == 'f'):
+                    if (c.ravel() > 1).any() or (c.ravel() < 0).any():
+                        raise ValueError(
+                            "number in rgba sequence is outside 0-1 range")
                     # looks like rgba already, nothing to be done; do
                     # we want to apply alpha here if
                     # (c[:,3]==1).all() ?
-                    return c
-            result = np.zeros((len(c), 4))
+                    return np.asarray(c, np.float)
+            # It must be some other sequence of color specs.
+            result = np.zeros((nc, 4), dtype=np.float)
             for i, cc in enumerate(c):
-                result[i] = self.to_rgba(cc, alpha)  # change in place
-        return np.asarray(result, np.float_)
+                result[i] = self.to_rgba(cc, alpha)
+            return result
 
 colorConverter = ColorConverter()
 


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Revision: 8308
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8308&view=rev
Author:   efiring
Date:     2010-05-11 20:23:04 +0000 (Tue, 11 May 2010)

Log Message:
-----------
close bug 2997687: integer overflow problem in Normalize

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2010-05-11 20:00:14 UTC (rev 8307)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2010-05-11 20:23:04 UTC (rev 8308)
@@ -796,11 +796,13 @@
         elif vmin==vmax:
             result = 0.0 * val
         else:
+            vmin = float(vmin)
+            vmax = float(vmax)
             if clip:
                 mask = ma.getmask(val)
                 val = ma.array(np.clip(val.filled(vmax), vmin, vmax),
                                 mask=mask)
-            result = (val-vmin) * (1.0/(vmax-vmin))
+            result = (val-vmin) / (vmax-vmin)
         if vtype == 'scalar':
             result = result[0]
         return result
@@ -809,6 +811,10 @@
         if not self.scaled():
             raise ValueError("Not invertible until scaled")
         vmin, vmax = self.vmin, self.vmax
+        if vmin >= vmax:
+            raise ValueError("Inversion requires valid vmax > vmin")
+        vmin = float(vmin)
+        vmax = float(vmax)
 
         if cbook.iterable(value):
             val = ma.asarray(value)
@@ -816,18 +822,17 @@
         else:
             return vmin + value * (vmax - vmin)
 
-
     def autoscale(self, A):
         '''
         Set *vmin*, *vmax* to min, max of *A*.
         '''
-        self.vmin = ma.minimum(A)
-        self.vmax = ma.maximum(A)
+        self.vmin = ma.min(A)
+        self.vmax = ma.max(A)
 
     def autoscale_None(self, A):
         ' autoscale only None-valued vmin or vmax'
-        if self.vmin is None: self.vmin = ma.minimum(A)
-        if self.vmax is None: self.vmax = ma.maximum(A)
+        if self.vmin is None: self.vmin = ma.min(A)
+        if self.vmax is None: self.vmax = ma.max(A)
 
     def scaled(self):
         'return true if vmin and vmax set'


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Revision: 8348
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8348&view=rev
Author:   efiring
Date:     2010-05-30 23:58:27 +0000 (Sun, 30 May 2010)

Log Message:
-----------
LogNorm.autoscale ignores nonpositive values; closes 2953069

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2010-05-30 21:31:19 UTC (rev 8347)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2010-05-30 23:58:27 UTC (rev 8348)
@@ -850,6 +850,8 @@
             vtype = 'scalar'
             val = ma.array([value]).astype(np.float)
 
+        val = ma.masked_less_equal(val, 0, copy=False)
+
         self.autoscale_None(val)
         vmin, vmax = self.vmin, self.vmax
         if vmin > vmax:
@@ -879,6 +881,24 @@
         else:
             return vmin * pow((vmax/vmin), value)
 
+    def autoscale(self, A):
+        '''
+        Set *vmin*, *vmax* to min, max of *A*.
+        '''
+        A = ma.masked_less_equal(A, 0, copy=False)
+        self.vmin = ma.min(A)
+        self.vmax = ma.max(A)
+
+    def autoscale_None(self, A):
+        ' autoscale only None-valued vmin or vmax'
+        if self.vmin is not None and self.vmax is not None:
+            return
+        A = ma.masked_less_equal(A, 0, copy=False)
+        if self.vmin is None:
+            self.vmin = ma.min(A)
+        if self.vmax is None:
+            self.vmax = ma.max(A)
+
 class BoundaryNorm(Normalize):
     '''
     Generate a colormap index based on discrete intervals.


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Revision: 8355
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8355&view=rev
Author:   efiring
Date:     2010-06-01 00:31:42 +0000 (Tue, 01 Jun 2010)

Log Message:
-----------
Colormap.__call__: override existing alpha only if alpha is specified.
Closes 2891982.  The color for masked data is still handled differently;
this may need to be changed.

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2010-05-31 23:05:55 UTC (rev 8354)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2010-06-01 00:31:42 UTC (rev 8355)
@@ -482,7 +482,7 @@
         self._isinit = False
 
 
-    def __call__(self, X, alpha=1.0, bytes=False):
+    def __call__(self, X, alpha=None, bytes=False):
         """
         *X* is either a scalar or an array (of any dimension).
         If scalar, a tuple of rgba values is returned, otherwise
@@ -490,18 +490,12 @@
         are integers, then they are used as indices into the array.
         If they are floating point, then they must be in the
         interval (0.0, 1.0).
-        Alpha must be a scalar.
+        Alpha must be a scalar between 0 and 1, or None.
         If bytes is False, the rgba values will be floats on a
         0-1 scale; if True, they will be uint8, 0-255.
         """
 
         if not self._isinit: self._init()
-        alpha = min(alpha, 1.0) # alpha must be between 0 and 1
-        alpha = max(alpha, 0.0)
-        self._lut[:-1,-1] = alpha  # Don't assign global alpha to i_bad;
-                                   # it would defeat the purpose of the
-                                   # default behavior, which is to not
-                                   # show anything where data are missing.
         mask_bad = None
         if not cbook.iterable(X):
             vtype = 'scalar'
@@ -532,7 +526,17 @@
         if bytes:
             lut = (self._lut * 255).astype(np.uint8)
         else:
-            lut = self._lut
+            lut = self._lut.copy()
+
+        if alpha is not None:
+            alpha = min(alpha, 1.0) # alpha must be between 0 and 1
+            alpha = max(alpha, 0.0)
+            lut[:-1,-1] = alpha  # Don't assign global alpha to i_bad;
+                                       # it would defeat the purpose of the
+                                       # default behavior, which is to not
+                                       # show anything where data are missing.
+
+
         rgba = np.empty(shape=xa.shape+(4,), dtype=lut.dtype)
         lut.take(xa, axis=0, mode='clip', out=rgba)
                     #  twice as fast as lut[xa];


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Revision: 8356
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8356&view=rev
Author:   efiring
Date:     2010-06-01 01:03:06 +0000 (Tue, 01 Jun 2010)

Log Message:
-----------
colors.py: more improvement in alpha handling for over, under, and bad values

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2010-06-01 00:31:42 UTC (rev 8355)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2010-06-01 01:03:06 UTC (rev 8356)
@@ -526,17 +526,21 @@
         if bytes:
             lut = (self._lut * 255).astype(np.uint8)
         else:
-            lut = self._lut.copy()
+            lut = self._lut.copy() # Don't let alpha modify original _lut.
 
         if alpha is not None:
             alpha = min(alpha, 1.0) # alpha must be between 0 and 1
             alpha = max(alpha, 0.0)
-            lut[:-1,-1] = alpha  # Don't assign global alpha to i_bad;
-                                       # it would defeat the purpose of the
-                                       # default behavior, which is to not
-                                       # show anything where data are missing.
+            if (lut[-1] == 0).all():
+                lut[:-1, -1] = alpha
+                # All zeros is taken as a flag for the default bad
+                # color, which is no color--fully transparent.  We
+                # don't want to override this.
+            else:
+                lut[:,-1] = alpha
+                # If the bad value is set to have a color, then we
+                # override its alpha just as for any other value.
 
-
         rgba = np.empty(shape=xa.shape+(4,), dtype=lut.dtype)
         lut.take(xa, axis=0, mode='clip', out=rgba)
                     #  twice as fast as lut[xa];
@@ -546,20 +550,20 @@
             rgba = tuple(rgba[0,:])
         return rgba
 
-    def set_bad(self, color = 'k', alpha = 1.0):
+    def set_bad(self, color = 'k', alpha = None):
         '''Set color to be used for masked values.
         '''
         self._rgba_bad = colorConverter.to_rgba(color, alpha)
         if self._isinit: self._set_extremes()
 
-    def set_under(self, color = 'k', alpha = 1.0):
+    def set_under(self, color = 'k', alpha = None):
         '''Set color to be used for low out-of-range values.
            Requires norm.clip = False
         '''
         self._rgba_under = colorConverter.to_rgba(color, alpha)
         if self._isinit: self._set_extremes()
 
-    def set_over(self, color = 'k', alpha = 1.0):
+    def set_over(self, color = 'k', alpha = None):
         '''Set color to be used for high out-of-range values.
            Requires norm.clip = False
         '''


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Revision: 8965
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8965&view=rev
Author:   efiring
Date:     2011-02-09 04:16:08 +0000 (Wed, 09 Feb 2011)

Log Message:
-----------
Normalize: major speed-up via bypassing masked array division

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2011-02-08 13:27:16 UTC (rev 8964)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2011-02-09 04:16:08 UTC (rev 8965)
@@ -853,8 +853,11 @@
                 mask = ma.getmask(result)
                 result = ma.array(np.clip(result.filled(vmax), vmin, vmax),
                                   mask=mask)
-            result -= vmin
-            result /= vmax - vmin
+            # ma division is very slow; we can take a shortcut
+            resdat = result.data
+            resdat -= vmin
+            resdat /= (vmax - vmin)
+            result = np.ma.array(resdat, mask=result.mask, copy=False)
         if is_scalar:
             result = result[0]
         return result


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Revision: 8968
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8968&view=rev
Author:   efiring
Date:     2011-02-10 01:21:27 +0000 (Thu, 10 Feb 2011)

Log Message:
-----------
bugfix: handle alpha correctly in colormapping with uint8

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2011-02-09 17:57:14 UTC (rev 8967)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2011-02-10 01:21:27 UTC (rev 8968)
@@ -547,6 +547,8 @@
         if alpha is not None:
             alpha = min(alpha, 1.0) # alpha must be between 0 and 1
             alpha = max(alpha, 0.0)
+            if bytes:
+                alpha = int(alpha * 255)
             if (lut[-1] == 0).all():
                 lut[:-1, -1] = alpha
                 # All zeros is taken as a flag for the default bad


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Revision: 8969
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8969&view=rev
Author:   efiring
Date:     2011-02-10 07:37:05 +0000 (Thu, 10 Feb 2011)

Log Message:
-----------
LogNorm: speed-up by dealing with mask explicitly

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

Modified: trunk/matplotlib/lib/matplotlib/colors.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/colors.py	2011-02-10 01:21:27 UTC (rev 8968)
+++ trunk/matplotlib/lib/matplotlib/colors.py	2011-02-10 07:37:05 UTC (rev 8969)
@@ -921,9 +921,17 @@
                                 mask=mask)
             #result = (ma.log(result)-np.log(vmin))/(np.log(vmax)-np.log(vmin))
             # in-place equivalent of above can be much faster
-            np.ma.log(result, result)
-            result -= np.log(vmin)
-            result /= (np.log(vmax) - np.log(vmin))
+            resdat = result.data
+            mask = result.mask
+            if mask is np.ma.nomask:
+                mask = (resdat <= 0)
+            else:
+                mask |= resdat <= 0
+            np.putmask(resdat, mask, 1)
+            np.log(resdat, resdat)
+            resdat -= np.log(vmin)
+            resdat /= (np.log(vmax) - np.log(vmin))
+            result = np.ma.array(resdat, mask=mask, copy=False)
         if is_scalar:
             result = result[0]
         return result


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