Matplotlib show|keep visible annotation line that disappears during pan/zoom?

Question

Consider this code:

import matplotlib as mpl
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.subplots()

ax.plot([1, 2, 3, 4], [0, 0.5, 1, 0.2])

ax.annotate("", xy=(0,0), xytext=(1,1), arrowprops=dict(facecolor='black'))

ax.set_ylabel('some numbers')
ax.set_xlim([0,5])
ax.set_ylim([0,2])
plt.show()

It produces this:

I drag a the window down a little bit with the mouse - and the line is completely gone - even if judging by the previous image, it should still be visible:

Apparently, matplotlib thinks that if the annotation line is not fully visible in the window, - that is, it is clippent - then it should be completely removed.

I think that if an annotation line is clipped, then it should be shown to the extent it is visible.

How to get matplotlib to do what I want, and not what it wants?

---

EDIT: just found about annotation_clip; if I set it to True, then behavior is same as above; if I set it to False; then I can get:

But that is not what I want either - what I want is this (photoshopped):

How the hell do I get this - how would you call it, clipped, non-clipped, half clipped, whatever the hell it is?

Answer 1

Found it: annotate problem when drawing arrows with segments out of axis · Issue #1402 · matplotlib/matplotlib · GitHub

The primary purpose of "annotate" is to annotate something with text and optionally with an arrow. And the current behavior is a feature that makes sense in most cases. For what you want, you need to adjust two things. First you should suppress the current behavior of annotation, and you can do this by setting "annotation_clip=False" (see the documentation for more details). You further need to clip the arrow with bbox of the axes. ...

And with that the corrected example from OP is:

import matplotlib as mpl
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.subplots()

ax.plot([1, 2, 3, 4], [0, 0.5, 1, 0.2])

annot = ax.annotate("", xy=(0,0), xytext=(1,1), arrowprops=dict(facecolor='black'), annotation_clip=False) # no clip_rect
annot.arrow_patch.set_clip_box(ax.bbox)

ax.set_ylabel('some numbers')
ax.set_xlim([0,5])
ax.set_ylim([0,2])
plt.show()