How to fix: "Attribute Qt::AA_EnableHighDpiScaling must be set before QCoreApplication is created." warning

Question

Anytime I try to plot anything with Matplotlib I get this warning.

Attribute Qt::AA_EnableHighDpiScaling must be set before QCoreApplication is created.

Does anyone know how to fix it?

Tried googling any issues related to Qt bindings in Matplotlib - still couldn't fix this.

Here is a simple code that would yield the warning

import numpy as np
import matplotlib.pyplot as plt

a = np.arange(1000) # the distribution doesn't matter
plt.hist(a) # here could plt.scatter or plt.plot - would still get same error.
plt.show()

Answer 1

This can be solved by updating matplotlib to the latest version. First, remove the older version using:

pip uninstall matplotlib

Then, install the latest version using:

pip install matplotlib

Answer 2

in QT you have some rules when setting application flags, and that is one of them,

you need to do something like (c++ as ref but in python is the same):

//first set the flags
QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
//more code and then create the QApplication 
QApplication mainApplication(argc, argv);