Make a discrete colormap from a continuous colormap

cmap_discretize.py

def cmap_discretize(cmap, N):
    """Return a discrete colormap from the continuous colormap cmap.
    
        cmap: colormap instance, eg. cm.jet. 
        N: number of colors.
    """
    if type(cmap) == str:
        cmap = get_cmap(cmap)
    colors_i = np.concatenate((np.linspace(0, 1., N), (0.,0.,0.,0.)))
    colors_rgba = cmap(colors_i)
    indices = np.linspace(0, 1., N+1)
    cdict = {}
    for ki, key in enumerate(('red','green','blue')):
        cdict[key] = [(indices[i], colors_rgba[i-1,ki], colors_rgba[i,ki]) for i in range(N+1)]
    # Return colormap object.
    return matplotlib.colors.LinearSegmentedColormap(cmap.name + "_%d"%N, cdict, 1024)