matplotlib颜色条 [英] matplotlib colorbar for scatter

问题描述

我使用的数据有数据有3个绘图参数：x，y，c。如何为散点图创建自定义颜色值？

I'm working with data that has the data has 3 plotting parameters: x,y,c. How do you create a custom color value for a scatter plot?

扩展此示例我想尝试：

import matplotlib
import matplotlib.pyplot as plt
cm = matplotlib.cm.get_cmap('RdYlBu')
colors=[cm(1.*i/20) for i in range(20)]
xy = range(20)
plt.subplot(111)
colorlist=[colors[x/2] for x in xy] #actually some other non-linear relationship
plt.scatter(xy, xy, c=colorlist, s=35, vmin=0, vmax=20)
plt.colorbar()
plt.show()

$ b b

但结果是 TypeError：必须先set_array for mappable

推荐答案

从散点图上的matplotlib文档 1 ：

From the matplotlib docs on scatter 1:

cmap仅在c是浮点数组时使用

cmap is only used if c is an array of floats

因此，colorlist需要是一个float列表，而不是你现在拥有的tuple列表。
plt.colorbar（）想要一个可映射的对象，就像Plt.scatter（）返回的CircleCollection。
vmin和vmax然后可以控制彩条的限制。

So colorlist needs to be a list of floats rather than a list of tuples as you have it now. plt.colorbar() wants a mappable object, like the CircleCollection that plt.scatter() returns. vmin and vmax can then control the limits of your colorbar. Things outside vmin/vmax get the colors of the endpoints.

这对于你是如何工作的？

How does this work for you?

import matplotlib.pyplot as plt
cm = plt.cm.get_cmap('RdYlBu')
xy = range(20)
z = xy
sc = plt.scatter(xy, xy, c=z, vmin=0, vmax=20, s=35, cmap=cm)
plt.colorbar(sc)
plt.show()

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