python - matplotlib color map - predefine mappings to values?

Question

I have an array that I am viewing using imshow(). (imsave() really, but the process should be identical).

I know that the values in the array will be between 0-9 and wonder if it is possible to use cmap to set each output to a specific 'color'. Perhaps by mapping these to a dict?

Answer 1

Just use a ListedColormap.

As a quick (but ugly) example:

import matplotlib.pyplot as plt
from matplotlib.colors import ListedColormap

cmap = ListedColormap(['red', 'green', 'blue', 'black'], 'indexed')

fig, ax = plt.subplots()
im = ax.imshow([range(4)], interpolation='none', cmap=cmap)
fig.colorbar(im)
plt.show()