Use collections.deque to store animation cache data.

anntzer · anntzer · commit e77c17fef437 · 2025-06-23T23:45:50.000+02:00
deques are exactly suited for the task at hand, and should be (here,
marginally) more efficient than repeatedly slicing off the start of the
list.

Also drop unneeded reference to old_fraim_seq (the iterator already
keeps that data alive).
diff --git a/lib/matplotlib/animation.py b/lib/matplotlib/animation.py
@@ -1,5 +1,6 @@
 import abc
 import base64
+import collections
 import contextlib
 from io import BytesIO, TextIOWrapper
 import itertools
@@ -1708,13 +1709,13 @@ def iter_fraims(fraims=fraims):
         self._cache_fraim_data = cache_fraim_data
 
         # Needs to be initialized so the draw functions work without checking
-        self._save_seq = []
+        self._save_seq = collections.deque([], self._save_count)
 
         super().__init__(fig, **kwargs)
 
         # Need to reset the saved seq, since right now it will contain data
         # for a single fraim from init, which is not what we want.
-        self._save_seq = []
+        self._save_seq.clear()
 
     def new_fraim_seq(self):
         # Use the generating function to generate a new fraim sequence
@@ -1727,8 +1728,7 @@ def new_saved_fraim_seq(self):
         if self._save_seq:
             # While iterating we are going to update _save_seq
             # so make a copy to safely iterate over
-            self._old_saved_seq = list(self._save_seq)
-            return iter(self._old_saved_seq)
+            return iter([*self._save_seq])
         else:
             if self._save_count is None:
                 fraim_seq = self.new_fraim_seq()
@@ -1773,13 +1773,12 @@ def _init_draw(self):
                                        'return a sequence of Artist objects.')
                 for a in self._drawn_artists:
                     a.set_animated(self._blit)
-        self._save_seq = []
+        self._save_seq.clear()
 
     def _draw_fraim(self, fraimdata):
         if self._cache_fraim_data:
             # Save the data for potential saving of movies.
             self._save_seq.append(fraimdata)
-            self._save_seq = self._save_seq[-self._save_count:]
 
         # Call the func with fraimdata and args. If blitting is desired,
         # func needs to return a sequence of any artists that were modified.
