Examples of non-interactive matplotlib backends with or without GUIs

README.md

Examples of non-interactive matplotlib backends with or without GUIs

It is first worth reading about backends in the matplotlib Usage Guide.

Non-interactive with GUI

Running

$ python with_gui.py
Interactive mode: False
matplotlib backend: TkAgg

will run load and show the GUI without stopping and then close it when the script finishes. Running

$ python -i with_gui.py

will keep the REPL running after the script executes and allow for further interaction and updating of the GUI.

Non-interactive without GUI

GUIs can be avoided by not using the GUI compatible matplotlib.pyplot APIs and using the matplotlib.figure.Figure APIs instead.

$ python without_gui.py
Interactive mode: False
matplotlib backend: TkAgg
Traceback (most recent call last):
  File "without_gui.py", line 17, in <module>
    fig.show()  # Errors as no GUI available
  File "/home/feickert/.pyenv/versions/base/lib/python3.8/site-packages/matplotlib/figure.py", line 407, in show
    raise AttributeError(
AttributeError: Figure.show works only for figures managed by pyplot, normally created by pyplot.figure()

Non-GUI backend (no GUI possible)

Or, as recommended by Thomas Caswell, set a non-GUI backend so that the GUI frameworks aren't even imported.

$ python nongui_backend.py
Interactive mode: False
matplotlib backend: agg
nongui_backend.py:20: UserWarning: Matplotlib is currently using agg, which is a non-GUI backend, so cannot show the figure.
  fig.show()  # Errors as no GUI possible

nongui_backend.py

import matplotlib
import matplotlib.pyplot as plt
import numpy as np

if __name__ == "__main__":
    print(f"Interactive mode: {matplotlib.is_interactive()}")
    # Agg is non-interactive and will not even import the GUI frameworks
    # c.f. https://matplotlib.org/stable/tutorials/introductory/usage.html#what-is-a-backend
    # c.f. https://twitter.com/tacaswell/status/1377122080664166408
    matplotlib.use("agg")
    print(f"matplotlib backend: {matplotlib.rcParams['backend']}")

    x = np.linspace(0, 10, 1000)
    y = np.sin(x)

    fig, ax = plt.subplots()
    ax.plot(x, y)
    fig.savefig("nongui_backend.png")

    fig.show()  # Errors as no GUI possible

requirements.txt

matplotlib~=3.3

with_gui.py

import matplotlib
import matplotlib.pyplot as plt
import numpy as np

if __name__ == "__main__":
    print(f"Interactive mode: {matplotlib.is_interactive()}")
    print(f"matplotlib backend: {matplotlib.rcParams['backend']}")

    x = np.linspace(0, 10, 1000)
    y = np.sin(x)

    fig, ax = plt.subplots()
    ax.plot(x, y)
    fig.savefig("with_gui.png")

    fig.show()  # Works as GUI available

without_gui.py

import matplotlib
import numpy as np
from matplotlib.figure import Figure

if __name__ == "__main__":
    print(f"Interactive mode: {matplotlib.is_interactive()}")
    print(f"matplotlib backend: {matplotlib.rcParams['backend']}")

    x = np.linspace(0, 10, 1000)
    y = np.sin(x)

    fig = Figure()
    ax = fig.subplots()
    ax.plot(x, y)
    fig.savefig("without_gui.png")

    fig.show()  # Errors as no GUI available