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?
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)
Rather than using set_cmap
, which requires a matplotlib.colors.Colormap
instance, you can set the cmap
directly in the pcolormesh
call
(cmaps.viridis
is a matplotlib.colors.ListedColormap
)
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])
imgplot = plt.pcolormesh(lum_img, cmap=cmaps.viridis)
What I did is to just copy the
_viridis_data = [[0.267004, 0.004874, 0.329415],
[0.268510, 0.009605, 0.335427],
[0.269944, 0.014625, 0.341379],
:
[0.983868, 0.904867, 0.136897],
[0.993248, 0.906157, 0.143936]]
from https://github.com/BIDS/colormap/blob/master/colormaps.py
and add:
from matplotlib.colors import ListedColormap
viridis = ListedColormap(_viridis_data, name='viridis')
plt.register_cmap(name='viridis', cmap=viridis)
plt.set_cmap(viridis)
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