Errno 20: Not a directory when saving into zip file

When I try to save a pyplot figure as a jpg, I keep getting a directory error saying that the given file name is not a directory. I am working in Colab. I have a numpy array called z_img and have opened a zip file.

import matplotlib.pyplot as plt
from zipfile import ZipFile

zipObj = ZipFile('slices.zip', 'w') # opening zip file
plt.imshow(z_img, cmap='binary')

The plotting works fine. I did a test of saving the image into Colab’s regular memory like so:

plt.savefig(str(ii)+'um_slice.jpg')

And this works perfectly, except I am intending to use this code in a for loop. ii is an index to differentiate between each image, and several hundred images would be created so I want them going in the zipfile. Now when I try adding the path to the zipfile:

plt.savefig('/content/slices.zip/'+str(ii)+'um_slice.jpg')

I get: NotADirectoryError: [Errno 20] Not a directory: ‘/content/slices.zip/150500um_slice.jpg’

I assume it’s because the {}.jpg string is a filename, and not a directory per se. But I am quite new to Python, and don’t know how to get the plot into the zip file. That’s all I want. Would love any advice!

>Solution :

From the docs, matplotlib.pyplot.savefig accepts a binary file-like object. ZipFile.open creates binary file like objects. These two have to get todgether!

with zipobj.open(str(ii)+'um_slice.jpg', 'w') as fp: 
    plt.savefig(fp)