Gallery

The NBSite gallery is a Sphinx extension to build a gallery from directory of notebook examples containing HoloViews plots. The extension creates thumbnails from Python scripts or Jupyter notebooks examples, builds a gallery index page and individual pages for each of the examples in the gallery. The nbsite.gallery can be activated like any other sphinx extension:

Activating the extension

To enable the extension add it to the list of extensions in conf.py:

extensions += ['nbsite.gallery']

Configuring the extension

The nbsite.gallery is primarily configured via the conf.py file by defining a nbsite_gallery_conf dictionary variable, offering the following options:

• backends

• default_extensions

• download_as

• enable_download

• examples_dir

• galleries

• github_org

• github_project

• host

• inline

• nblink

• only_use_existing

• skip_execute

• orphans

• thumbnail_url

• within_subsection_order

• skip_rst_notebook_directive

A sample configuration might look something like this:

nbsite_gallery_conf = {
  'backends': ['bokeh', 'matplotlib'],
      'default_extensions': ['*.ipynb', '*.py'],
      'enable_download': True,
  'examples_dir': os.path.join('..', 'examples'),
  'galleries': {
    'gallery': {'title': 'Gallery'}
  },
  'github_org': 'pyviz',
  'github_project': 'geoviews',
      'thumbnail_url': 'https://assets.holoviews.org/thumbnails',
  'within_subsection_order': lambda key: key
}

File extension

The nbsite.gallery can handle two different file types:

• *.py files containing a Python script

• *.ipynb files containing a Jupyter notebook

The default_extensions variable defaults to include both but may be narrowed down to a single file type.

Directory structure

The most important variables when configuring the gallery are the examples_dir and galleries keys, which define the location and structure of the galleries. The examples_dir variable should define the location of the examples directory relative to the conf.py file. By default it assumes that relative to the project root the doc and examples directories are in ./doc and ./examples respectively.

The galleries config variable should be specified as a nested dictionary defining one or more galleries to build. To illustrate this let us look at a sample galleries configuration:

'galleries': {
  'gallery': {
    'backends': [],
    'extensions': ['*.ipynb', '*.py'],
    'intro': 'Sample intro',
    'title': 'A sample gallery title',
    'sections': [],
   }
 }

Combined with examples_dir variable this declares that it should look for the examples in ./examples/gallery directory. Beyond that a number of different nesting structures are possible depending on the defined backends and sections. Defining sections declares that the examples are further nested into subdirectories, while declaring backends either at the top level or the in the galleries config declares that there are multiple plotting backends to toggle between. Depending on what is declared the following directory structure are therefore valid:

./examples_dir/gallery_name/section/backend/example.ipynb
./examples_dir/gallery_name/section/example.ipynb
./examples_dir/gallery_name/backend/example.ipynb
./examples_dir/gallery_name/example.ipynb

Note that if there are multiple backends they must be declared but the sections will be discovered automatically if not defined.

Section structure

A section may either be declared as a string or a dictionary which allows further customization on a per-section basis. If the section is declared as a string it is assumed it matches sections path and will be upgraded to title case to add a section header. The dictionary structure should look like this:

{'backends': ['bokeh'], 'path': 'section_a', 'skip': True,
     'title': 'Section A', 'within_subsection_order': lambda key: key}

The most important parts of the declaration provide the path and title of the subsection. The skip key declares whether the examples in the subsection should actually be executed, which is sometimes not practical, e.g. for bokeh apps. Alternatively the examples which should not be executed can also be explicitly declared using the global skip_execute config variable.

The skip key can also be used to pass a list of files that should not show up at all on the gallery page. These examples will not be thumbnailed or executed.

A slight variation on skip, the orphans key allows the user to pass a list of files that will be rendered to html without being thumbnailed and linked from the gallery page. The main usecase for this is when a section has an index which provides an overview of the section and directs users through the notebooks in a particular order.

The actual ordering of the examples in each subsection is defined by the global or section specific within_subsection_order config variable, which should define a key function which defines the sort order.

Gallery backends

The backends feature in nbsite.gallery is built around the capability of HoloViews to output plots using multiple plotting backends. A gallery which declares multiple backends will have a set of toggle buttons added at the top which will allow choosing between the different backends.

Gallery page

To control the look and feel of your gallery landing page, you can use set the inline option to True. This will make the sections render inline on the landing page increasing the density of content for projects that have few notebooks per section (for instance: examples.pyviz.org).

Thumbnail downloads

In some cases it isn’t practical to automatically generate a thumbnail for a plot, particularly if it demonstrates some interactive feature. For such cases nbsite.gallery offers the option to fetch the thumbnail from a remote URL which should match the directory structure of the examples_dir, which may be defined under the thumbnail_url config variable, e.g. for the holoviews thumbnails are stored under https://assets.holoviews.org/thumbnails. To toggle this behavior on and off you can set the enable_downloads config variable.

If you want to be sure never to generate thumbnails, for instance if the environment won’t have the right dependencies, then use the only_use_existing to ensure that the script can only use thumbnails found in the directory or at thumbnail_url.

Asset Download

Each example links back to the location of the script or notebook it was built from. These download links can be placed at the top, bottom or both of the notebook using the nblink option. By default the download usses GitHub as the host, in order to correctly determine these links the github_org and github_project must be defined, declaring the GitHub organization and repository respectively.

To enable direct downloads from the assets directory of the website set host to assets. By default the links will point to a particular file. To instead point the download link to a project archive, set download_as to project.