DOC: Fix resizing of animation examples

QuLogic · QuLogic · commit 60a2b9229a83 · 2023-10-05T17:23:04.000-04:00
On resize, either `init_func` will be called, or if not defined, the
main `func` with `i=0` is called. On animations that save a state, the
latter can cause weird glitching as the history will skip around.

* For `bayes_update`, I fixed it by providing an `init_func`.
* For `double_pendulum`, I fixed it by simplifying the trace line (since
  we have the entire history pre-computed.
diff --git a/galleries/examples/animation/bayes_update.py b/galleries/examples/animation/bayes_update.py
@@ -41,6 +41,11 @@ def __init__(self, ax, prob=0.5):
         # which the plotted distribution should converge.
         self.ax.axvline(prob, linestyle='--', color='black')
 
+    def start(self):
+        # Used for the *init_func* parameter of FuncAnimation; this is called when
+        # initializing the animation, and also after resizing the figure.
+        return self.line,
+
     def __call__(self, i):
         # This way the plot can continuously run and we just keep
         # watching new realizations of the process
@@ -62,5 +67,5 @@ def __call__(self, i):
 
 fig, ax = plt.subplots()
 ud = UpdateDist(ax, prob=0.7)
-anim = FuncAnimation(fig, ud, frames=100, interval=100, blit=True)
+anim = FuncAnimation(fig, ud, init_func=ud.start, frames=100, interval=100, blit=True)
 plt.show()
diff --git a/galleries/examples/animation/double_pendulum.py b/galleries/examples/animation/double_pendulum.py
@@ -92,19 +92,14 @@ def derivs(t, state):
 trace, = ax.plot([], [], '.-', lw=1, ms=2)
 time_template = 'time = %.1fs'
 time_text = ax.text(0.05, 0.9, '', transform=ax.transAxes)
-history_x, history_y = deque(maxlen=history_len), deque(maxlen=history_len)
 
 
 def animate(i):
     thisx = [0, x1[i], x2[i]]
     thisy = [0, y1[i], y2[i]]
 
-    if i == 0:
-        history_x.clear()
-        history_y.clear()
-
-    history_x.appendleft(thisx[2])
-    history_y.appendleft(thisy[2])
+    history_x = x2[:i]
+    history_y = y2[:i]
 
     line.set_data(thisx, thisy)
     trace.set_data(history_x, history_y)
