无法使用matplotlib.use('Agg')，图形始终显示在屏幕上 [英] Can't use matplotlib.use('Agg'), graphs always show on the screen

问题描述

我正在研究matplotlib，不知道如何只保存图形而不将其打印在屏幕上.

I'm studying matplotlib and don't know how to just save the graph and not print it on the screen.

因此，我已经在Internet上进行了一些研究，许多答案都说解决方案是matplotlib.use('Agg').而且必须在导入matplotlib.pyplot或pylab之前.

So I've done some research on the Internet, many answers said the solution is matplotlib.use('Agg'). And it must be before importing matplotlib.pyplot or pylab.

然后，当我将其添加到脚本的第一行时，它根本无法工作.

Then when I added it in the first line of my script, it doesn't work at all.

import matplotlib
matplotlib.use('Agg') 
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt

E:\Program Files\Anaconda3\lib\site-packages\matplotlib\__init__.py:1401: UserWarning:  This call to matplotlib.use() has no effect
because the backend has already been chosen;
matplotlib.use() must be called *before* pylab, matplotlib.pyplot,
or matplotlib.backends is imported for the first time.

  warnings.warn(_use_error_msg)

我使用Anaconda Spyder，所以我重新启动内核并再次运行我的脚本，我得到了同样的错误信息.

I use Anaconda Spyder, so I restarted kernel and ran my script again, I got same wrong information.

然后，我再次重新启动内核，并在控制台中直接键入以下代码:

Then I restarted kernel again and directly typed the following code in the console:

In[1]: import matplotlib as mpl

In[2]: mpl.use('Agg')

E:\Program Files\Anaconda3\lib\site-packages\matplotlib\__init__.py:1401: UserWarning:  This call to matplotlib.use() has no effect
because the backend has already been chosen;
matplotlib.use() must be called *before* pylab, matplotlib.pyplot,
or matplotlib.backends is imported for the first time.

  warnings.warn(_use_error_msg)

此外，如果我在脚本末尾删除'plt.show()'或添加'plt.ioff()'，该图将始终显示在屏幕上.

Also, if I delete 'plt.show()' at the end of script or add 'plt.ioff()', the graph will always print on the screen.

感谢大家的回答.现在，我有两种解决方案:

Thanks for everyone's answer. Now I have two solutions:

1. 只需使用plt.close()，就不会更改后端，并且图形也不会显示.

1. just use plt.close() , this will not change the backend and the figure doesn't show up.

使用plt.switch_backend('Agg')，这会将后端切换为"agg"，并且屏幕上不打印任何数字.

use plt.switch_backend('Agg'), this will switch the backend to 'agg' and no figure printed on the screen.

推荐答案

您可以尝试切换后端.显然，Spyder会先加载matplotlib，而use无效.这可能会有所帮助: 如何在matplotlib/Python中切换后端

You can try to switch the backend. Apparently Spyder loads matplotlib before you do, and use has no effect. This may be helpful: How to switch backends in matplotlib / Python

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