Merge pull request matplotlib#2650 from syngron/master

Lightsource shade method parameters for color range definition

Author: pelson

lib/matplotlib/colors.py

@@ -1355,17 +1355,20 @@ def __init__(self, azdeg=315, altdeg=45,
         self.hsv_min_sat = hsv_min_sat
         self.hsv_max_sat = hsv_max_sat
 
-    def shade(self, data, cmap):
+    def shade(self, data, cmap, norm=None):
         """
         Take the input data array, convert to HSV values in the
         given colormap, then adjust those color values
-        to given the impression of a shaded relief map with a
+        to give the impression of a shaded relief map with a
         specified light source.
         RGBA values are returned, which can then be used to
         plot the shaded image with imshow.
         """
 
-        rgb0 = cmap((data - data.min()) / (data.max() - data.min()))
+        if norm is None:
+            norm = Normalize(vmin=data.min(), vmax=data.max())
+
+        rgb0 = cmap(norm(data))
         rgb1 = self.shade_rgb(rgb0, elevation=data)
         rgb0[:, :, 0:3] = rgb1
         return rgb0

lib/matplotlib/tests/test_colors.py

@@ -205,6 +205,34 @@ def gray_from_float_rgba():
     assert_raises(ValueError, gray_from_float_rgba)
 
 
+def test_light_source_shading_color_range():
+    # see also
+    #http://matplotlib.org/examples/pylab_examples/shading_example.html
+
+    from matplotlib.colors import LightSource
+    from matplotlib.colors import Normalize
+
+    refinput = np.array([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]])
+    norm = Normalize(vmin=0, vmax=50)
+    ls = LightSource(azdeg=0, altdeg=65)
+    testoutput = ls.shade(refinput, plt.cm.jet, norm=norm)
+    refoutput = np.array([
+        [[0., 0., 0.58912656, 1.],
+        [0., 0., 0.67825312, 1.],
+        [0., 0., 0.76737968, 1.],
+        [0., 0., 0.85650624, 1.]],
+        [[0., 0., 0.9456328, 1.],
+        [0., 0., 1., 1.],
+        [0., 0.04901961, 1., 1.],
+        [0., 0.12745098, 1., 1.]],
+        [[0., 0.22156863, 1., 1.],
+        [0., 0.3, 1., 1.],
+        [0., 0.37843137, 1., 1.],
+        [0., 0.45686275, 1., 1.]]
+        ])
+    assert_array_almost_equal(refoutput, testoutput)
+
+
 if __name__ == '__main__':
     import nose
     nose.runmodule(argv=['-s', '--with-doctest'], exit=False)