How to use viridis in matplotlib 1.4

python matplotlib colormap
ukrutt picture ukrutt · Sep 9, 2015 · Viewed 28.2k times · Source

I want to use the colormap "viridis" (http://bids.github.io/colormap/), and I won't be updating to the development version 1.5 quite yet. Thus, I have downloaded colormaps.py from https://github.com/BIDS/colormap. Unfortunately, I'm not able to make it work. This is what I do:

import matplotlib.pyplot as plt
import matplotlib.image as mpimg
import numpy as np

import colormaps as cmaps

img=mpimg.imread('stinkbug.png')
lum_img = np.flipud(img[:,:,0])

plt.set_cmap(cmaps.viridis)
imgplot = plt.pcolormesh(lum_img)

This gives me a ValueError, the traceback ending with,

ValueError: Colormap viridis is not recognized. Possible values are: Spectral, summer, coolwarm, ...

(And then the complete list of originally installed colormaps.)

Any thoughts on how to fix this issue?

Answer

aganders3 picture aganders3 · Sep 9, 2015

To set viridis as your colormap using set_cmap, you must register it first:

import colormaps as cmaps
plt.register_cmap(name='viridis', cmap=cmaps.viridis)
plt.set_cmap(cmaps.viridis)

img=mpimg.imread('stinkbug.png')
lum_img = np.flipud(img[:,:,0])
imgplot = plt.pcolormesh(lum_img)

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