How to change backends in matplotlib / Python

Question

I am struggling with the following issue. I need to generate reports that consists of a collection of charts. All these charts, except one, are made using Matplotlib default backend (TkAgg). One chart needs to be made using the Cairo backend, the reason is that I am plotting an igraph graph and that can only be plotted using Cairo.

The issue is that I cannot change backends on the fly, for example the following does not work:
matplotlib.pyplot.switch_backend('cairo.png') (I know that the switch_backend functionality is experimental)

and I have also tried matplotlib.use("cairo.png") but this leads to import problems as the matplotlib.use("cairo.png") statement should come before importing matplotlib.pyplot. but I need two different backends over the course of the life of the script.

So my question is does someone have a code snippet that shows how to switch the backend in Matplotlib?

Thanks so much!

UPDATE: I have written a snippet that loads matplotlib, shows the default backend, unloads matplotlib, reloads it and changes the backend:

import matplotlib import matplotlib.pyplot as plt import sys print matplotlib.pyplot.get_backend()  modules = [] for module in sys.modules:     if module.startswith('matplotlib'):         modules.append(module)  for module in modules:     sys.modules.pop(module)  import matplotlib matplotlib.use("cairo.png") import matplotlib.pyplot as plt  print matplotlib.pyplot.get_backend() 

but is this really the way to do it?

UPDATE 2: I had some serious brain freeze yesterday... The simple and most obvious solution is to use the Cairo backend for all charts and not to switch the backend at all :)

UPDATE 3: Actually, it's still an issue so anybody who knows how to dynamically switch matplotlib backends....please post your answer.

Answer 1

Six years later and I came across a similar issue, when trying to decide which backend was available to use.
Note see Caveats - below

This code snippet works well for me:

import matplotlib gui_env = ['TKAgg','GTKAgg','Qt4Agg','WXAgg'] for gui in gui_env:     try:         print "testing", gui         matplotlib.use(gui,warn=False, force=True)         from matplotlib import pyplot as plt         break     except:         continue print "Using:",matplotlib.get_backend()  Using: GTKAgg 

As you can deduce, swapping the backend is as simple as re-importing matplotlib.pyplot after forcing the new backend

matplotlib.use('WXAgg',warn=False, force=True) from matplotlib import pyplot as plt print "Switched to:",matplotlib.get_backend()  Switched to: WXAgg 

For those still having trouble, this code will print out the:
list of Non Gui backends;
the list of Gui backends;
and then attempt to use each Gui backend to see if it is present and functioning.

import matplotlib gui_env = [i for i in matplotlib.rcsetup.interactive_bk] non_gui_backends = matplotlib.rcsetup.non_interactive_bk print ("Non Gui backends are:", non_gui_backends) print ("Gui backends I will test for", gui_env) for gui in gui_env:     print ("testing", gui)     try:         matplotlib.use(gui,warn=False, force=True)         from matplotlib import pyplot as plt         print ("    ",gui, "Is Available")         plt.plot([1.5,2.0,2.5])         fig = plt.gcf()         fig.suptitle(gui)         plt.show()         print ("Using ..... ",matplotlib.get_backend())     except:         print ("    ",gui, "Not found") 

Caveats: Changes in matplotlib since version 3.3.0

• The first parameter of matplotlib.use has been renamed from arg to backend (only relevant if you pass by keyword).
• The parameter warn of matplotlib.use has been removed. A failure to switch the backend will now always raise an ImportError if force is set; catch that error if necessary.
• All parameters of matplotlib.use except the first one are now keyword-only.