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Eriz11 opened this issue Mar 4, 2019 · 2 comments
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Same environment but different results with saving/loading a pickled figure #13586

Eriz11 opened this issue Mar 4, 2019 · 2 comments
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Community support Users in need of help. Documentation

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@Eriz11
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Eriz11 commented Mar 4, 2019

I faced an issue regarding how to load a figure after pickling it. I don't know if this might be a bug (in VSCode), the very nature of the package or other things.

The saving process of the figure goes smoothly. Code for reference:

with open('cdImg.pickle', 'wb') as f:
                pickle.dump(f1, f)

However, when I load the figure in Ipython with the following code:

In [1]: import pickle

In [2]: import matplotlib.pyplot as plt

In [3]: candleFig = pickle.load(open('cdImg.pickle', 'rb'))

In [4]: candleFig.show() ### Here plt.show() also works.

The image shows perfectly. Using that same code in VSCode (within the same env; hence, same python and package versions) I don't get the figure, but the program executes perfectly and without any error.

In contrast, if I execute the following in VSCode:

import pickle
import matplotlib.pyplot as plt

def loadImage():
   
   candleFig = pickle.load(open('cdImg.pickle', 'rb'))
       
   plt.show() ### In the IPython example it was: candleFig.show()
   
if __name__ == '__main__':
   
   loadImage()

It loads the image perfectly. Notice the change from candleFig in ipython to plt.show() in VSCode.

¿Is there anything I'm missing about the candleFig.show() not working in VSCode?

Matplotlib version: 3.0.2
Python version: 3.6.8
Ipython: 6.4.0
Pickle version: 4.0
@timhoffm
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timhoffm commented Mar 4, 2019 •
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Figure.show() is quite different from plt.show(); see e.g. #13101 (comment) For your use case you should use plt.show() in both situations.

Actually, the environments are not the same. VSCode runs the code in a simple python shell. Ipython does magic in the background. I don't know what exactly, but for sure it's responsible that Figure.show() works in an interactive shell as well.

The difference between Figure.show() and plt.show() should probably be documented better.

@timhoffm timhoffm added Community support Users in need of help. Documentation labels Mar 4, 2019
@Eriz11
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Eriz11 commented Mar 4, 2019

Hi Tim,

Many thanks for the comments. I will stick with the plt.show() option as it looks like (after reading the referenced comment) handles all the caveats for the end-user more easily.

In regard to the difference in environments, you are totally right. I tried to highlight that the versions were the same in both cases; but my comment was not totally correct technically speaking.

I could consider this as closed if you (or others) don't have anything else to add.

Again, thanks for the quick show up.

@QuLogic QuLogic closed this as completed Mar 4, 2019
@timhoffm timhoffm mentioned this issue Mar 5, 2019
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