Matplotlib backend selection

Introduction

Matplotlib backend selection decides how and where your charts and graphs are shown or saved. It helps you choose the best way to display or create images depending on your needs.

You want to show a graph in a window on your computer screen.

You need to save a plot as an image file without opening a window.

You are working on a server without a display and want to create plots.

You want to embed plots inside a web page or a notebook.

You want faster rendering for interactive use or better quality for printing.

Syntax

Matplotlib

import matplotlib
matplotlib.use('backend_name')

Replace 'backend_name' with the name of the backend you want to use, like 'TkAgg', 'Agg', or 'Qt5Agg'.

You must call matplotlib.use() before importing matplotlib.pyplot.

Examples

This sets the backend to TkAgg, which opens plots in a window on your computer.

Matplotlib

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

This sets the backend to Agg, which creates image files without opening any window.

Matplotlib

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

This uses the Qt5Agg backend for interactive plots with Qt5 support.

Matplotlib

import matplotlib
matplotlib.use('Qt5Agg')
import matplotlib.pyplot as plt

Sample Program

This program sets the backend to 'Agg' so it does not open a window. It creates a simple line plot and saves it as 'plot.png'. Finally, it prints a message to confirm the file was saved.

Matplotlib

import matplotlib
matplotlib.use('Agg')  # Use Agg backend for file output
import matplotlib.pyplot as plt

plt.plot([1, 2, 3], [4, 5, 6])
plt.title('Simple Line Plot')
plt.savefig('plot.png')
print('Plot saved as plot.png')

Important Notes

Changing the backend after importing matplotlib.pyplot will not work and may cause errors.

Common backends include 'TkAgg', 'Qt5Agg', 'Agg', 'MacOSX', and 'WebAgg'. Choose based on your environment and needs.

Use matplotlib.get_backend() to check which backend is currently active.

Summary

Matplotlib backend controls how plots are displayed or saved.

Set the backend before importing pyplot using matplotlib.use().

Choose a backend that fits your environment: interactive window, file output, or web embedding.