


Generating a PNG with matplotlib When DISPLAY is Undefined
Problem:
When attempting to create a PNG image using matplotlib without a DISPLAY environment variable defined, you may encounter errors indicating that matplotlib cannot locate a suitable backend.
Cause:
matplotlib defaults to using an X-based backend, which requires a valid DISPLAY variable. When DISPLAY is undefined, matplotlib will raise an error.
Solution: Use the 'Agg' Backend
To resolve this issue, force matplotlib to use the "Agg" backend, which does not require a graphical display. This can be achieved by adding the following code before any other matplotlib imports:
import matplotlib # Force matplotlib to not use any Xwindows backend. matplotlib.use('Agg')
Explanation:
The Agg backend is a non-interactive backend that provides a way to save figures as files without the need for a graphical display. By setting matplotlib to use this backend, you can generate PNG images even without a valid DISPLAY variable.
Alternative Solutions:
- Set the DISPLAY variable to a valid display device.
- Use a different Python module that does not rely on matplotlib for image generation.
- Set the backend in the .matplotlibrc file:
backend : Agg
The above is the detailed content of How to Generate PNG Images with Matplotlib When DISPLAY is Undefined?. For more information, please follow other related articles on the PHP Chinese website!

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