Documentation¶

Contributions to Bokeh will only be accepted if they contain sufficient and appropriate documentation support. This section outlines how to build and edit documentation locally, as well as describes conventions that the project adheres to.

Helping with documentation is one of the most valuable ways to contribute to a project. It’s also a good way to to get started and introduce yourself as a new contributor. The most likely way for typos or other small documentation errors to be resolved is for the person who notices the problem to immediately submit a Pull Request to with a correction. This is always appreciated! In addition to quick fixes, there is also a list of Open Docs Issues on GitHub that anyone can look at for tasks that need help.

Working on Documentation¶

Sphinx is used to generate HTML documentation. Due to the innate dependency of Bokeh on JavaScript, no other output formats are supported by the official build configuration. This section describes how to use Sphinx to build the Bokeh documentation from source.

Install requirements¶

In order to build the docs from source, you should have followed the instructions in Getting Set Up.

Some of the Bokeh examples in the documentation rely on sample data that is not included in the Bokeh GitHub repository or released packages, due to their size.

Once Bokeh is installed, the sample data can be obtained by executing the following command at a Bash or Windows prompt:

bokeh sampledata

See Sample Data for alternative instructions on how to download the sample data.

Build the Documentation¶

To generate the full documentation, first navigate to the sphinx subdirectory of the Bokeh source tree.

cd sphinx

Sphinx uses the make tool to control the build process. The most common targets or the Bokeh makefile are:

clean: Remove all previously built documentation output. All outputs will be generated from scratch on the next build.
html: Build any HTML output that is not built, or needs re-building (e.g. because the input source file has changed since the last build)
serve: Start a server to serve the docs open a web browser to display. Note that due to the JavaScript files involved, starting a real server is necessary to view many portions of the docs fully.

For example, clean the docs build directory, run the follow command at the command line:

make clean

Multiple targets may be combined in a single make invocation. For instance, executing the following command will clean the docs build, generate all HTML docs from scratch, then open a browser to display the results:

make clean html serve

By default, built docs will load the most recent BokehJS from CDN. If you are making local changes to the BokehJS and wish to have the docs use your locally built BokehJS instead, you can set the environment variable BOKEH_DOCS_CDN before calling make:

BOKEH_DOCS_CDN=local make clean html serve

Building the docs also requires setting up the GOOGLE_API_KEY environment variable that gmap plots use. You can create a new API Key. Or if you don’t care whether gmap plots work, you can set the variable with a fake value before calling make:

GOOGLE_API_KEY=foo make clean html serve

Source Code Documentation¶

Docstrings and Model help are available from a Python interpreter, but are also processed by the Sphinx build to automatically generate a complete Reference.

Bokeh uses some common conventions to create a consistent documentation style.

Docstrings¶

We use Sphinx Napoleon to process docstrings for our reference documentation.

All docstrings are Google Style Docstrings. Docstrings should generally begin with a verb stating what the function or method does in a short statement. For example, the “verb first” style is preferred:

""" Create and return a new Foo. (GOOD)

"""

over the more verbose sentence below:

""" This function creates and returns a new Foo. (BAD)

"""

Docstrings for functions and methods should generally include the following sections:

Args (unless the function takes no arguments)
Returns (even if the function just returns None)

Short descriptions for parameters should be written in such a way that inserting an implicit “IS” makes a complete sentence. For example:

title_font (str, optional) :
    A font used for the plot title (default: Sans)

can be reasonably read as “title_font IS a font used for the plot title”.

A complete example might look like:

def somefunc(name, level):
    ''' Create and return a new Foo.

    Args:
        name (str) :
            A name for the Foo

        level (int) :
            A level for the Foo to be configured for

    Returns:
        Foo

    '''

Models and Properties¶

Bokeh’s Model system supports its own system for providing detailed documentation for individual properties. These are given as a help argument to the property type, which is interpreted as standard Sphinx ReST when the reference documentation is built. For example:

class DataRange(Range):
    ''' A base class for all data range types.

    '''

    names = List(String, help="""
    A list of names to query for. If set, only renderers that
    have a matching value for their ``name`` attribute will be used
    for autoranging.
    """)

    renderers = List(Instance(Renderer), help="""
    An explicit list of renderers to autorange against. If unset,
    defaults to all renderers on a plot.
    """)

Narrative Documentation¶

The narrative documentation consists of all the documentation that is not automatically generated from docstrings and Bokeh property helpstrings. This includes User’s Guide, Quickstart, etc. The source code for these docs are standard Sphinx Restructure Text (ReST) files that are located under the sphinx/source/docs subdirectory of the source tree.

Section Headings¶

In narrative documentation, headings help the users follow the key points and sections. The following outlines the headings hierarchy:

Top level
=========

This will add a "Top Level" entry in the navigation sidebar

Second level
------------

This may add a sub-entry in the sidebar, depending on configuration.

Third level
~~~~~~~~~~~

Fourth level
''''''''''''

Note that the length of the underline must match that of the heading text, or else the Sphinx build will fail.

Release Notes¶

Each release should add a new file under sphinx/source/docs/releases that briefly describes the changes in the release including any migration notes. The filename should be <version>.rst, for example sphinx/source/docs/releases/0.12.7.rst. The Sphinx build will automatically add this content to the list of all releases.