Matplotlib python 更改颜色图中的单一颜色 [英] Matplotlib python change single color in colormap
问题描述
我使用 python 中的颜色图来绘制和分析矩阵中的值.我需要将白色与等于0.0的每个元素相关联,而对于其他元素,我希望具有传统"颜色图.查看 Python Matplotlib Colormap 我将 pcolor 使用的字典修改为:
I use the colormap in python to plot and analyse values in a matrix. I need to associate the white color to each element equal to 0.0 while for others I'd like to have a "traditional" color map. Looking at Python Matplotlib Colormap I modified the dictionary used by pcolor as:
dic = {'red': ((0., 1, 1),
(0.00000000001, 0, 0),
(0.66, 1, 1),
(0.89,1, 1),
(1, 0.5, 0.5)),
'green': ((0., 1, 1),
(0.00000000001, 0, 0),
(0.375,1, 1),
(0.64,1, 1),
(0.91,0,0),
(1, 0, 0)),
'blue': ((0., 1, 1),
(0.00000000001, 1, 1),
(0.34, 1, 1),
(0.65,0, 0),
(1, 0, 0))}
结果是:
我设置:
matrix[0][0]=0 matrix[0][1]=0.002
但是,您可以看到它们都与白色相关联,即使我将0.00000000001设置为蓝色的起点也是如此.这怎么可能?如何更改它以获得我想要的东西?
But as you can see they are both associated with the white color, even if I set 0.00000000001 as the starting point for the blue. How is this possible? How can I change it in order to obtain what I'd like?
推荐答案
虽然不理想,但屏蔽零值是有效的.您可以使用 cmap.set_bad()
控制它的显示.
Although not ideal, masking the zero value works. You can control the display of it with the cmap.set_bad()
.
from matplotlib.colors import LinearSegmentedColormap
import matplotlib.pyplot as plt
import numpy as np
dic = {'red': ((0., 1, 0),
(0.66, 1, 1),
(0.89,1, 1),
(1, 0.5, 0.5)),
'green': ((0., 1, 0),
(0.375,1, 1),
(0.64,1, 1),
(0.91,0,0),
(1, 0, 0)),
'blue': ((0., 1, 1),
(0.34, 1, 1),
(0.65,0, 0),
(1, 0, 0))}
a = np.random.rand(10,10)
a[0,:2] = 0
a[0,2:4] = 0.0001
fig, ax = plt.subplots(1,1, figsize=(6,6))
cmap = LinearSegmentedColormap('custom_cmap', dic)
cmap.set_bad('white')
ax.imshow(np.ma.masked_values(a, 0), interpolation='none', cmap=cmap)
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