Defining a binary matplotlib colormap

Question

I'm trying to use the matplotlib.imshow to plot a boolean 2d array and I'd like to be able to pick the two colours (one for true and one for false). It seems that this argument should be passed as a colormap to imshow but in my case it seems a bit of an overkill as I don't need continuous and, more important, I don't know how to define a custom colormap (the matplotlib doc hasn't helped me with that).

can you link to the doc that you were reading and explain what wasn't clear? — Paul H, Oct 28 '14 at 20:41
You can make color maps with a discrete number of steps, just use 2 for binary data — tacaswell, Oct 28 '14 at 20:49
http://stackoverflow.com/questions/14777066/matplotlib-discrete-colorbar — tacaswell, Oct 28 '14 at 20:50

score 28 · Accepted Answer · answered Dec 15 '20 at 11:48

28

import matplotlib.pyplot as plt
import matplotlib.colors

# Color for False and True
cmap = matplotlib.colors.ListedColormap(['red', 'green'])

plt.imshow([True, False], [False, True]], cmap=cmap)

answered Dec 15 '20 at 11:48

DieterDP

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SpongeBob narrator: "Six years later..." – Mr. T Dec 15 '20 at 12:13
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Indeed, 6years since I asked that. Finally I can close this and move on with my life =) – Learning is a mess Dec 15 '20 at 14:46

Defining a binary matplotlib colormap

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