matplotlib - 如何让颜色条从暗到亮缩放？

Question

使用下面的代码，我绘制了两个矩形 block ，其颜色与算术值匹配。我已经包含了一个用于解释数据值的颜色条。如何使颜色条缩放为:深蓝色 --> 白色？

 import matplotlib.pyplot as plt
 import matplotlib.patches as patches
 from matplotlib import cm
 from matplotlib.colors import Normalize
 import numpy as np

 f,ax=plt.subplots()  
 blues=plt.get_cmap('Blues')

 norm = Normalize(vmin=0, vmax=2)
 sm = plt.cm.ScalarMappable(cmap=blues, norm=norm)
 sm._A = []
 ax.add_patch(patches.Rectangle((2,2),width=4.5, height=4, 
 facecolor=blues(norm(2)), alpha=1,label='a'))
 ax.add_patch(patches.Rectangle((2,-2),width=4.5, height=4, 
 facecolor=blues(norm(0.9)), alpha=1,label='b'))

 plt.colorbar(sm)
 plt.show()
 plt.xlim(xmin=-10,xmax=10)
 plt.ylim(ymin=-10,ymax=10)

 plt.show()

example output

Answer 1

对于任何内置颜色图，您可以将 _r 附加到其名称末尾以获取反转的颜色图。因此，请将 blues=plt.get_cmap('Blues') 替换为 blues=plt.get_cmap('Blues_r')。

有关引用，请参见 this page 的底部:

This reference example shows all colormaps included with Matplotlib. Note that any colormap listed here can be reversed by appending "_r" (e.g., "pink_r").