DOC: fix inaccuracy in colormap tutorial

jklymak · greglucas · jklymak · commit 303881de93cb · 2021-11-23T17:00:53.000+01:00
Co-authored-by: Greg Lucas &lt;greg.m.lucas@gmail.com&gt;
diff --git a/tutorials/colors/colormap-manipulation.py b/tutorials/colors/colormap-manipulation.py
@@ -132,12 +132,14 @@ def plot_examples(colormaps):
 plot_examples([viridis, newcmp])
 
 ##############################################################################
-# We can easily reduce the dynamic range of a colormap; here we choose the
-# middle 0.5 of the colormap.  However, we need to interpolate from a larger
-# colormap, otherwise the new colormap will have repeated values.
-
-viridis_big = cm.get_cmap('viridis', 512)
-newcmp = ListedColormap(viridis_big(np.linspace(0.25, 0.75, 256)))
+# We can reduce the dynamic range of a colormap; here we choose the
+# middle half of the colormap.  Note, however, that because viridis is a
+# listed colormap, we will end up with 128 discrete values instead of the 256
+# values that were in the original colormap. This method does not interpolate
+# in color-space to add new colors.
+
+viridis_big = cm.get_cmap('viridis')
+newcmp = ListedColormap(viridis_big(np.linspace(0.25, 0.75, 128)))
 plot_examples([viridis, newcmp])
 
 ##############################################################################
