[Python] When I tried to use matplotlib for graph drawing, I got the error "this application failed to start because it could not find or load the qt platform plugin" windows "".

• I made a note as a personal memorandum. I would appreciate it if you could point out anything wrong.

problem

test_graph1(A program that graphs a function).py

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 10, 500)
y = np.sin(x)

plt.figure()
plt.plot(x, y)
plt.show()

When you do the above

This application failed to start because it could not find or load the Qt platform plugin "windows" in "". Reinstalling the application may fix this problem.

Error message appeared and I fell into a state where I could not draw a graph.

environment

Windows 10 Home Python 3.7.7 Visual Studio Code 1.44.2 Anaconda 4.8.3

Solution

From the conclusion, installing Qt, SIP and PyQt5 solved it.

Install Qt open source from here and Execute the following on the console such as the command prompt.

$ pip install SIP

$ pip install PyQt5

WARNING: You are using pip version 19.2.3, however version 20.0.2 is available. You should consider upgrading via the 'python -m pip install --upgrade pip' command.

If you get a WARNING like the one above, do the following:

$ python -m pip install --upgrade pip

This will install PyQt5 correctly and If you execute test_graph1 (program that draws the graph of the function) .py </ font> again, the graph will be displayed. This is the error that occurred because the Qt dll was not installed correctly. (For Anaconda environment, it is recommended to install with conda command instead of pip command.)

from PyQt5.QtWidget import QWidget, QApplication