MNT: use set logic rather than list comprehension to filter backend list

tacaswell · QuLogic · web-flow · commit 73c0df7099b2 · 2019-10-25T08:25:34.000-04:00
Co-Authored-By: Elliott Sales de Andrade &lt;quantum.analyst@gmail.com&gt;
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
@@ -2248,7 +2248,7 @@ def getname_val(identifier):
 # is compatible with the current running interactive framework.
 if (rcParams["backend_fallback"]
         and dict.__getitem__(rcParams, "backend") in [
-            k for k in _interactive_bk if k not in ['WebAgg', 'nbAgg']]
+       and dict.__getitem__(rcParams, "backend") in (set(_interactive_bk) - {'WebAgg', 'nbAgg'})
         and cbook._get_running_interactive_framework()):
     dict.__setitem__(rcParams, "backend", rcsetup._auto_backend_sentinel)
 # Set up the backend.
