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

tacaswell · QuLogic · tacaswell · commit 0eaa2db9b22e · 2019-10-30T22:00:36.000-04:00
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
@@ -2244,8 +2244,8 @@ def getname_val(identifier):
 # requested, ignore rcParams['backend'] and force selection of a backend that
 # 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.
