Remove qt4 backends from backend fallback candidates.

anntzer · anntzer · commit aaacd25b2add · 2020-05-13T19:45:36.000+02:00
This avoids triggering a deprecation warning whenever backend fallback
occurs, even if the fallback mechanism was not going to select qt4foo.
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
@@ -234,8 +234,7 @@ def switch_backend(newbackend):
         # Don't try to fallback on the cairo-based backends as they each have
         # an additional dependency (pycairo) over the agg-based backend, and
         # are of worse quality.
-        for candidate in [
-                "macosx", "qt5agg", "qt4agg", "gtk3agg", "tkagg", "wxagg"]:
+        for candidate in ["macosx", "qt5agg", "gtk3agg", "tkagg", "wxagg"]:
             try:
                 switch_backend(candidate)
             except ImportError:
diff --git a/matplotlibrc.template b/matplotlibrc.template
@@ -65,9 +65,10 @@
 ## ***************************************************************************
 ## The default backend.  If you omit this parameter, the first working
 ## backend from the following list is used:
-##     MacOSX Qt5Agg Qt4Agg Gtk3Agg TkAgg WxAgg Agg
+##     MacOSX Qt5Agg Gtk3Agg TkAgg WxAgg Agg
 ## Other choices include:
-##     Qt5Cairo Qt4Cairo GTK3Cairo TkCairo WxCairo Cairo Wx
+##     Qt5Cairo GTK3Cairo TkCairo WxCairo Cairo
+##     Qt4Agg Qt4Cairo Wx  # deprecated.
 ##     PS PDF SVG Template
 ## You can also deploy your own backend outside of matplotlib by referring to
 ## the module name (which must be in the PYTHONPATH) as 'module://my_backend'.
