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Specifying Thumbnails in conf.py

This notebook doesn’t contain any thumbnail metadata.

But in the file conf.py, a thumbnail is specified (via the nbsphinx_thumbnails option), which will be used in the gallery.

The keys in the nbsphinx_thumbnails dictionary can contain wildcards, which behave very similarly to the html_sidebars option.

The thumbnail files can be local image files somewhere in the source directory, but you’ll need to create at least one link to them in order to copy them to the HTML output directory.

You can also use files from the _static directory (which contains all files in your html_static_path).

If you want, you can also use files from the _images directory, which contains all notebook outputs.

To demonstrate this feature, we are creating an image file here:

[1]:
%matplotlib agg
/home/docs/checkouts/readthedocs.org/user_builds/nbsphinx/envs/better-theme/lib/python3.7/site-packages/traitlets/traitlets.py:3036: FutureWarning: --rc={'figure.dpi': 96} for dict-traits is deprecated in traitlets 5.0. You can pass --rc <key=value> ... multiple times to add items to a dict.
  FutureWarning,
[2]:
import matplotlib.pyplot as plt
[3]:
fig, ax = plt.subplots()
ax.plot([4, 8, 15, 16, 23, 42])
fig.savefig('a-local-file.png')

Please note that the previous cell doesn’t have any outputs, but it has generated a file named a-local-file.png in the notebook’s directory.

We have to create a link to this file (which is a good idea anyway): a-local-file.png.

Now we can use this file in our conf.py like this:

nbsphinx_thumbnails = {
    'gallery/thumbnail-from-conf-py': 'gallery/a-local-file.png',
}

Please note that the notebook name does not contain the .ipynb suffix.