.. _documenting-matplotlib: ===================== Writing documentation ===================== Getting started =============== Installing dependencies ----------------------- The documentation for Matplotlib is generated from reStructuredText using the Sphinx_ documentation generation tool. There are several extra requirements that are needed to build the documentation. They are listed in :file:`doc-requirements.txt` and listed below: 1. Sphinx 1.3 or later (1.5.0 is not supported) 2. numpydoc 0.4 or later 3. IPython 4. mock 5. colorspacious 6. Pillow 7. Graphviz .. note:: * You'll need a minimal working LaTeX distribution for many examples to run. * `Graphviz `_ is not a Python package, and needs to be installed separately. General file structure ---------------------- All documentation is built from the :file:`doc/` directory. This directory contains both ``.rst`` files that contain pages in the documentation and configuration files for Sphinx_. The ``.rst`` files are kept in :file:`doc/users`, :file:`doc/devel`, :file:`doc/api` and :file:`doc/faq`. The main entry point is :file:`doc/index.rst`, which pulls in the :file:`index.rst` file for the users guide, developers guide, api reference, and FAQs. The documentation suite is built as a single document in order to make the most effective use of cross referencing. .. note:: An exception to this are the directories :file:`examples` and :file:`tutorials`, which exist in the root directory. These contain Python files that are built by `Sphinx Gallery`_. When the docs are built, the directories :file:`docs/gallery` and :file:`docs/tutorials` are automatically generated. Do not edit the rst files in :file:docs/gallery and :file:docs/tutorials, as they are rebuilt from the original sources in the root directory. Additional files can be added to the various guides by including their base file name (the .rst extension is not necessary) in the table of contents. It is also possible to include other documents through the use of an include statement, such as:: .. include:: ../../TODO The configuration file for Sphinx is :file:`doc/conf.py`. It controls which directories Sphinx parses, how the docs are built, and how the extensions are used. Building the docs ----------------- The documentation sources are found in the :file:`doc/` directory in the trunk. To build the documentation in html format, cd into :file:`doc/` and run: .. code-block:: sh python make.py html The list of commands and flags for ``make.py`` can be listed by running ``python make.py --help``. In particular, * ``python make.py clean`` will delete the built Sphinx files. Use this command if you're getting strange errors about missing paths or broken links, particularly if you move files around. * ``python make.py latex`` builds a PDF of the documentation. * The ``--allowsphinxwarnings`` flag allows the docs to continue building even if Sphinx throws a warning. This is useful for debugging and spot-checking many warnings at once. .. _formatting-mpl-docs: Writing new documentation ========================= Most documentation lives in "docstrings". These are comment blocks in source code that explain how the code works. All new or edited docstrings should conform to the numpydoc guidelines. These split the docstring into a number of sections - see https://github.com/numpy/numpy/blob/master/doc/HOWTO_DOCUMENT.rst.txt for more details and a guide to how docstrings should be formatted. An example docstring looks like: .. code-block:: python def hlines(self, y, xmin, xmax, colors='k', linestyles='solid', label='', **kwargs): """ Plot horizontal lines at each *y* from *xmin* to *xmax*. Parameters ---------- y : scalar or sequence of scalar y-indexes where to plot the lines. xmin, xmax : scalar or 1D array_like Respective beginning and end of each line. If scalars are provided, all lines will have same length. colors : array_like of colors, optional, default: 'k' linestyles : ['solid' | 'dashed' | 'dashdot' | 'dotted'], optional label : string, optional, default: '' Returns ------- lines : `~matplotlib.collections.LineCollection` Other Parameters ---------------- **kwargs : `~matplotlib.collections.LineCollection` properties. See also -------- vlines : vertical lines axhline: horizontal line across the axes """ The Sphinx website also contains plenty of documentation_ concerning ReST markup and working with Sphinx in general. .. note:: Some parts of the documentation do not yet conform to the current documentation style. If in doubt, follow the rules given here and not what you may see in the source code. Pull requests updating docstrings to the current style are very welcome. Additional formatting conventions --------------------------------- There are some additional conventions, not handled by numpydoc and the Sphinx guide: * We do not have a convention whether to use single-quotes or double-quotes. There is a mixture of both in the current code. Please leave them as they are. * Long parameter lists should be wrapped using a ``\`` for continuation and starting on the new line without any indent: .. code-block:: python def add_axes(self, *args, **kwargs): """ ... Parameters ---------- projection : ['aitoff' | 'hammer' | 'lambert' | 'mollweide' | \ 'polar' | 'rectilinear'], optional The projection type of the axes. Alternatively, you can describe the valid parameter values in a dedicated section of the docstring. * Generally, do not add markup to types for ``Parameters`` and ``Returns``. This is usually not needed because Sphinx will link them automatically and would unnecessarily clutter the docstring. However, it does seem to fail in some situations. If you encounter such a case, you are allowed to add markup: .. code-block:: rst Returns ------- lines : `~matplotlib.collections.LineCollection` Linking to other code --------------------- To link to other methods, classes, or modules in Matplotlib you can encase the name to refer to in back ticks, for example: .. code-block:: python `~matplotlib.collections.LineCollection` It is also possible to add links to code in Python, Numpy, Scipy, or Pandas. Sometimes it is tricky to get external Sphinx linking to work; to check that a something exists to link to the following shell command outputs a list of all objects that can be referenced (in this case for Numpy):: python -m sphinx.ext.intersphinx 'https://docs.scipy.org/doc/numpy/objects.inv' Function arguments ------------------ Function arguments and keywords within docstrings should be referred to using the ``*emphasis*`` role. This will keep Matplotlib's documentation consistent with Python's documentation: .. code-block:: rst Here is a description of *argument* Please do not use the ```default role```: .. code-block:: rst Please do not describe `argument` like this. nor the ````literal```` role: .. code-block:: rst Please do not describe ``argument`` like this. Setters and getters ------------------- Matplotlib uses artist introspection of docstrings to support properties. All properties that you want to support through `~.pyplot.setp` and `~.pyplot.getp` should have a ``set_property`` and ``get_property`` method in the `~.matplotlib.artist.Artist` class. The setter methods use the docstring with the ACCEPTS token to indicate the type of argument the method accepts. e.g., in `.Line2D`: .. code-block:: python # in lines.py def set_linestyle(self, linestyle): """ Set the linestyle of the line ACCEPTS: [ '-' | '--' | '-.' | ':' | 'steps' | 'None' | ' ' | '' ] """ Keyword arguments ----------------- Since Matplotlib uses a lot of pass-through ``kwargs``, e.g., in every function that creates a line (`~.pyplot.plot`, `~.pyplot.semilogx`, `~.pyplot.semilogy`, etc...), it can be difficult for the new user to know which ``kwargs`` are supported. Matplotlib uses a docstring interpolation scheme to support documentation of every function that takes a ``**kwargs``. The requirements are: 1. single point of configuration so changes to the properties don't require multiple docstring edits. 2. as automated as possible so that as properties change, the docs are updated automatically. The function `matplotlib.artist.kwdoc` and the decorator `matplotlib.docstring.dedent_interpd` facilitate this. They combine Python string interpolation in the docstring with the Matplotlib artist introspection facility that underlies ``setp`` and ``getp``. The ``kwdoc`` function gives the list of properties as a docstring. In order to use this in another docstring, first update the ``matplotlib.docstring.interpd`` object, as seen in this example from `matplotlib.lines`: .. code-block:: python # in lines.py docstring.interpd.update(Line2D=artist.kwdoc(Line2D)) Then in any function accepting `~.Line2D` pass-through ``kwargs``, e.g., `matplotlib.axes.Axes.plot`: .. code-block:: python # in axes.py @docstring.dedent_interpd def plot(self, *args, **kwargs): """ Some stuff omitted The kwargs are Line2D properties: %(Line2D)s kwargs scalex and scaley, if defined, are passed on to autoscale_view to determine whether the x and y axes are autoscaled; default True. See Axes.autoscale_view for more information """ Note there is a problem for `~matplotlib.artist.Artist` ``__init__`` methods, e.g., `matplotlib.patches.Patch.__init__`, which supports ``Patch`` ``kwargs``, since the artist inspector cannot work until the class is fully defined and we can't modify the ``Patch.__init__.__doc__`` docstring outside the class definition. There are some some manual hacks in this case, violating the "single entry point" requirement above -- see the ``docstring.interpd.update`` calls in `matplotlib.patches`. Adding figures ============== Figures in the documentation are automatically generated from scripts. It is not necessary to explicitly save the figure from the script; this will be done automatically when the docs are built to ensure that the code that is included runs and produces the advertised figure. There are two options for where to put the code that generates a figure. If you want to include a plot in the examples gallery, the code should be added to the :file:`examples` directory. Plots from the :file:`examples` directory can then be referenced through the symlink ``mpl_examples`` in the ``doc`` directory, e.g.: .. code-block:: rst .. plot:: mpl_examples/lines_bars_and_markers/fill.py Alternatively the plotting code can be placed directly in the docstring. To include plots directly in docstrings, see the following guide: Plot directive documentation ---------------------------- .. automodule:: matplotlib.sphinxext.plot_directive :no-undoc-members: Examples -------- The source of the files in the :file:`examples` directory are automatically run and their output plots included in the documentation. To exclude an example from having an plot generated insert "sgskip" somewhere in the filename. Adding animations ================= We have a Matplotlib Google/Gmail account with username ``mplgithub`` which we used to setup the github account but can be used for other purposes, like hosting Google docs or Youtube videos. You can embed a Matplotlib animation in the docs by first saving the animation as a movie using :meth:`matplotlib.animation.Animation.save`, and then uploading to `matplotlib's Youtube channel `_ and inserting the embedding string youtube provides like: .. code-block:: rst .. raw:: html An example save command to generate a movie looks like this .. code-block:: python ani = animation.FuncAnimation(fig, animate, np.arange(1, len(y)), interval=25, blit=True, init_func=init) ani.save('double_pendulum.mp4', fps=15) Contact Michael Droettboom for the login password to upload youtube videos of google docs to the mplgithub account. .. _referring-to-mpl-docs: Referring to data files ======================= In the documentation, you may want to include to a data file in the Matplotlib sources, e.g., a license file or an image file from :file:`mpl-data`, refer to it via a relative path from the document where the rst file resides, e.g., in :file:`users/navigation_toolbar.rst`, you can refer to the image icons with:: .. image:: ../../lib/matplotlib/mpl-data/images/subplots.png In the :file:`users` subdirectory, if you want to refer to a file in the :file:`mpl-data` directory, you can use the symlink directory. For example, from :file:`customizing.rst`:: .. literalinclude:: ../../lib/matplotlib/mpl-data/matplotlibrc One exception to this is when referring to the examples directory. Relative paths are extremely confusing in the sphinx plot extensions, so it is easier to simply include a symlink to the files at the top doc level directory. This way, API documents like :meth:`matplotlib.pyplot.plot` can refer to the examples in a known location. In the top level :file:`doc` directory we have symlinks pointing to the Matplotlib :file:`examples`: .. code-block:: sh home:~/mpl/doc> ls -l mpl_* mpl_examples -> ../examples So we can include plots from the examples dir using the symlink: .. code-block:: rst .. plot:: mpl_examples/pylab_examples/simple_plot.py .. _internal-section-refs: Internal section references =========================== To maximize internal consistency in section labeling and references, use hyphen separated, descriptive labels for section references, e.g.: .. code-block:: rst .. _howto-webapp: and refer to it using the standard reference syntax: .. code-block:: rst See :ref:`howto-webapp` Keep in mind that we may want to reorganize the contents later, so please try to avoid top level names in references like ``user`` or ``devel`` or ``faq`` unless necessary, because for example the FAQ "what is a backend?" could later become part of the users guide, so the label: .. code-block:: rst .. _what-is-a-backend is better than: .. code-block:: rst .. _faq-backend In addition, since underscores are widely used by Sphinx itself, please use hyphens to separate words. Section name formatting ======================= For everything but top level chapters, please use ``Upper lower`` for section titles, e.g., ``Possible hangups`` rather than ``Possible Hangups`` Generating inheritance diagrams =============================== Class inheritance diagrams can be generated with the ``inheritance-diagram`` directive. To use it, provide the directive with a number of class or module names (separated by whitespace). If a module name is provided, all classes in that module will be used. All of the ancestors of these classes will be included in the inheritance diagram. A single option is available: *parts* controls how many of parts in the path to the class are shown. For example, if *parts* == 1, the class ``matplotlib.patches.Patch`` is shown as ``Patch``. If *parts* == 2, it is shown as ``patches.Patch``. If *parts* == 0, the full path is shown. Example: .. code-block:: rst .. inheritance-diagram:: matplotlib.patches matplotlib.lines matplotlib.text :parts: 2 .. inheritance-diagram:: matplotlib.patches matplotlib.lines matplotlib.text :parts: 2 .. _emacs-helpers: Emacs helpers ============= There is an emacs mode `rst.el `_ which automates many important ReST tasks like building and updating table-of-contents, and promoting or demoting section headings. Here is the basic ``.emacs`` configuration: .. code-block:: lisp (require 'rst) (setq auto-mode-alist (append '(("\\.txt$" . rst-mode) ("\\.rst$" . rst-mode) ("\\.rest$" . rst-mode)) auto-mode-alist)) Some helpful functions:: C-c TAB - rst-toc-insert Insert table of contents at point C-c C-u - rst-toc-update Update the table of contents at point C-c C-l rst-shift-region-left Shift region to the left C-c C-r rst-shift-region-right Shift region to the right .. TODO: Add section about uploading docs .. _Sphinx: http://www.sphinx-doc.org .. _documentation: http://www.sphinx-doc.org/contents.html .. _`inline markup`: http://www.sphinx-doc.org/markup/inline.html .. _index: http://www.sphinx-doc.org/markup/para.html#index-generating-markup .. _`Sphinx Gallery`: https://sphinx-gallery.readthedocs.io/en/latest/