如何为hist2d图添加颜色条 [英] How to add a colorbar for a hist2d plot

问题描述

好吧，当我直接使用 matplotlib.pyplot.plt 创建图形时，我知道如何向图形添加颜色条.

Well, I know how to add a colour bar to a figure, when I have created the figure directly with matplotlib.pyplot.plt.

from matplotlib.colors import LogNorm
import matplotlib.pyplot as plt
import numpy as np

# normal distribution center at x=0 and y=5
x = np.random.randn(100000)
y = np.random.randn(100000) + 5

# This works
plt.figure()
plt.hist2d(x, y, bins=40, norm=LogNorm())
plt.colorbar()

但是以下原因为何不起作用，我需要在 colorbar(..)的调用中添加哪些内容才能使其正常工作.

But why does the following not work, and what would I need to add to the call of colorbar(..) to make it work.

fig, ax = plt.subplots()
ax.hist2d(x, y, bins=40, norm=LogNorm())
fig.colorbar()
# TypeError: colorbar() missing 1 required positional argument: 'mappable'

fig, ax = plt.subplots()
ax.hist2d(x, y, bins=40, norm=LogNorm())
fig.colorbar(ax)
# AttributeError: 'AxesSubplot' object has no attribute 'autoscale_None'

fig, ax = plt.subplots()
h = ax.hist2d(x, y, bins=40, norm=LogNorm())
plt.colorbar(h, ax=ax)
# AttributeError: 'tuple' object has no attribute 'autoscale_None'

推荐答案

第三个选项就快到了.您必须将 mappable 对象传递给 colorbar ，这样它才能知道要提供colorbar的颜色图和限制.可以是 AxesImage 或 QuadMesh 等.

You are almost there with the 3rd option. You have to pass a mappable object to colorbar so it knows what colormap and limits to give the colorbar. That can be an AxesImage or QuadMesh, etc.

对于 hist2D，在您的 h 中返回的元组包含该 mappable ，也包含其他一些内容.

In the case of hist2D, the tuple returned in your h contains that mappable, but also some other things too.

来自文档:

退货:返回值为 (counts, xedges, yedges, Image).

Returns: The return value is (counts, xedges, yedges, Image).

因此，要制作颜色条，我们只需要 Image .

So, to make the colorbar, we just need the Image.

要修改您的代码，请执行以下操作:

To fix your code:

from matplotlib.colors import LogNorm
import matplotlib.pyplot as plt
import numpy as np

# normal distribution center at x=0 and y=5
x = np.random.randn(100000)
y = np.random.randn(100000) + 5

fig, ax = plt.subplots()
h = ax.hist2d(x, y, bins=40, norm=LogNorm())
fig.colorbar(h[3], ax=ax)

或者:

counts, xedges, yedges, im = ax.hist2d(x, y, bins=40, norm=LogNorm())
fig.colorbar(im, ax=ax)

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