Reverse colormap in matplotlib

In matplotlib a color map isn't a list, but it contains the list of its colors as colormap.colors. And the module matplotlib.colors provides a function ListedColormap() to generate a color map from a list. So you can reverse any color map by doing

colormap_r = ListedColormap(colormap.colors[::-1])

The solution is pretty straightforward. Suppose you want to use the "autumn" colormap scheme. The standard version:

cmap = matplotlib.cm.autumn

To reverse the colormap color spectrum, use get_cmap() function and append '_r' to the colormap title like this:

cmap_reversed = matplotlib.cm.get_cmap('autumn_r')

The standard colormaps also all have reversed versions. They have the same names with _r tacked on to the end. (Documentation here.)

As of Matplotlib 2.0, there is a reversed() method for ListedColormap and LinearSegmentedColorMap objects, so you can just do

cmap_reversed = cmap.reversed()

Here is the documentation.