Why plt.get_fignums() returns nothing when runs as a single line in a spyder ipython shell?

Question

I know there are "current figure" and "current axes" in matplotlib but if I run the following code line by line in a spyder ipython console, the "plt.get_fignums()" always returns an empty list. If the "current figure" and "current axes" are cleared after each run, why do the plt.gcf() and plt.gca() still return something? Does that mean matplotlib always keeps a blank figure and axes when initialized? Does it has anything to do with the "interactive mode" of matplotlib?

import matplotlib.pyplot as plt

plt.figure()
print(plt.get_fignums())
print(plt.gcf(),plt.gca())

Update:I make the code simpler to demo the problem

Python 3.7.3 (default, Apr 24 2019, 15:29:51) [MSC v.1915 64 bit (AMD64)] Type "copyright", "credits" or "license" for more information.

IPython 7.6.1 -- An enhanced Interactive Python.

In [1]: runfile('xxx.py', wdir='xxx')

[1]
Figure(432x288) AxesSubplot(0.125,0.125;0.775x0.755)

In [2]: print(plt.get_fignums())
   ...: print(plt.gcf(),plt.gca())
[]
Figure(432x288) AxesSubplot(0.125,0.125;0.775x0.755)

In [6]: plt.figure()
   ...: print(plt.get_fignums())
[1]
<Figure size 432x288 with 0 Axes>

In [7]: print(plt.get_fignums())
[]

[I cannot reproduce this](https://i.stack.imgur.com/JBNsq.png). Can you add more details? — ImportanceOfBeingErnest, Nov 10 '19 at 01:48
@ImportanceOfBeingErnest I saw your pic but the problem does exist in my environment. I posted the raw response text from my console. Not sure if it is about the ipython version? — Shawn Chen, Nov 10 '19 at 02:55
So you don't actually type in the code, but `runfile` it? That would mean that the pyplot state is cleared after the file is completed. In cell [2] you then have a clean new state with no open pyplot figures. — ImportanceOfBeingErnest, Nov 10 '19 at 02:58
@ImportanceOfBeingErnest Now I typed the code but it is still the same. — Shawn Chen, Nov 10 '19 at 03:31
Wait, maybe [this is](https://stackoverflow.com/questions/45760693/how-to-overlay-plots-from-different-cells) your problem? — ImportanceOfBeingErnest, Nov 10 '19 at 03:51
@ImportanceOfBeingErnest Thank you! It works now. It seems there is a lot to read before I can thoroughly understand what's wrong. — Shawn Chen, Nov 10 '19 at 08:43

Why plt.get_fignums() returns nothing when runs as a single line in a spyder ipython shell?

0 Answers0