matplotlib 和后端“agg”导致绘图未显示

Question

我正在尝试将 matplotlib 与 Pycharm Community Ed 一起使用。 2019.3，Python 3.7.3，Ubuntu 19.04。

import matplotlib
import matplotlib.pyplot as plt

plt.figure()
plt.plot(3,2,'.')
plt.show()

但是得到以下错误代码：UserWarning：Matplotlib 当前正在使用 agg，这是一个非 GUI 后端，因此无法显示该图。”

我尝试将后端更改为“NbAgg”：

import matplotlib
matplotlib.use('NbAgg')
import matplotlib.pyplot as plt

plt.figure()
plt.plot(3,2,'.')
plt.show()

但是得到以下错误代码：

 Traceback (most recent call last):
  File "/home/leo/.PyCharmCE2019.3/config/scratches/scratch_1.py", line 7, in <module>
    plt.show()
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/pyplot.py", line 269, in show
    return _show(*args, **kw)
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/backends/backend_nbagg.py", line 261, in show
    manager.show()
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/backends/backend_nbagg.py", line 90, in show
    self._create_comm()
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/backends/backend_nbagg.py", line 122, in _create_comm
    self.add_web_socket(comm)
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/backends/backend_webagg_core.py", line 432, in add_web_socket
    self.resize(w, h)
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/backends/backend_webagg_core.py", line 418, in resize
    size=(w / self.canvas._dpi_ratio, h / self.canvas._dpi_ratio))
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/backends/backend_webagg_core.py", line 489, in _send_event
    s.send_json(payload)
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/backends/backend_nbagg.py", line 199, in send_json
    self.comm.send({'data': json.dumps(content)})
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/ipykernel/comm/comm.py", line 123, in send
    data=data, metadata=metadata, buffers=buffers,
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/ipykernel/comm/comm.py", line 66, in _publish_msg
    self.kernel.session.send(self.kernel.iopub_socket, msg_type,
AttributeError: 'NoneType' object has no attribute 'session'
Error in atexit._run_exitfuncs:
Traceback (most recent call last):
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/_pylab_helpers.py", line 73, in destroy_all
    manager.destroy()
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/backends/backend_nbagg.py", line 126, in destroy
    self._send_event('close')
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/backends/backend_webagg_core.py", line 489, in _send_event
    s.send_json(payload)
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/matplotlib/backends/backend_nbagg.py", line 199, in send_json
    self.comm.send({'data': json.dumps(content)})
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/ipykernel/comm/comm.py", line 123, in send
    data=data, metadata=metadata, buffers=buffers,
  File "/home/leo/PycharmProjects/Coursera/venv/lib/python3.7/site-packages/ipykernel/comm/comm.py", line 66, in _publish_msg
    self.kernel.session.send(self.kernel.iopub_socket, msg_type,
AttributeError: 'NoneType' object has no attribute 'session'

我知道后端和显示图不兼容，但我不明白我需要做什么来匹配后端和显示图。

Answer 1

我能够将后端更改为“TkAgg”，但我必须使用以下命令通过命令行安装 tk：

sudo apt-get install python3-tk

但是，仍然需要使用 plt.show() 来弹出图形