Add Roadmap and CoC to the documentation (#3129)

* Move "Resources" into "Getting Started"

* Add "About" section with roadmap stub and code-of-conduct policy

* Add Roadmap section

---------

Co-authored-by: Mattijn van Hoek <[email protected]>
Co-authored-by: Stefan Binder <[email protected]>

doc/about/code_of_conduct.rst

@@ -0,0 +1,127 @@
+Code of Conduct
+===============
+
+Our Pledge
+----------
+We as members, contributors, and leaders pledge to make participation in our
+community a harassment-free experience for everyone, regardless of age, body
+size, visible or invisible disability, ethnicity, sex characteristics, gender
+identity and expression, level of experience, education, socio-economic status,
+nationality, personal appearance, race, caste, color, religion, or sexual
+identity and orientation.
+
+We pledge to act and interact in ways that contribute to an open, welcoming,
+diverse, inclusive, and healthy community.
+
+Our Standards
+-------------
+Examples of behavior that contributes to a positive environment for our
+community include:
+
+- Demonstrating empathy and kindness toward other people
+- Being respectful of differing opinions, viewpoints, and experiences
+- Giving and gracefully accepting constructive feedback
+- Accepting responsibility and apologizing to those affected by our mistakes,
+  and learning from the experience
+- Focusing on what is best not just for us as individuals, but for the overall
+  community
+
+Examples of unacceptable behavior include:
+
+- The use of sexualized language or imagery, and sexual attention or advances of
+  any kind
+- Trolling, insulting or derogatory comments, and personal or political attacks
+- Public or private harassment
+- Publishing others' private information, such as a physical or email address,
+  without their explicit permission
+- Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+Enforcement Responsibilities
+----------------------------
+Community leaders are responsible for clarifying and enforcing our standards of
+acceptable behavior and will take appropriate and fair corrective action in
+response to any behavior that they deem inappropriate, threatening, offensive,
+or harmful.
+
+Community leaders have the right and responsibility to remove, edit, or reject
+comments, commits, code, wiki edits, issues, and other contributions that are
+not aligned to this Code of Conduct, and will communicate reasons for moderation
+decisions when appropriate.
+
+Scope
+-----
+This Code of Conduct applies within all community spaces, and also applies when
+an individual is officially representing the community in public spaces.
+Examples of representing our community include using an official e-mail address,
+posting via an official social media account, or acting as an appointed
+representative at an online or offline event.
+
+Enforcement
+-----------
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported to the community leaders responsible for enforcement at
+[email protected].
+All complaints will be reviewed and investigated promptly and fairly.
+
+All community leaders are obligated to respect the privacy and security of the
+reporter of any incident.
+
+Enforcement Guidelines
+----------------------
+Community leaders will follow these Community Impact Guidelines in determining
+the consequences for any action they deem in violation of this Code of Conduct:
+
+1. Correction
+~~~~~~~~~~~~~
+**Community Impact**: Use of inappropriate language or other behavior deemed
+unprofessional or unwelcome in the community.
+
+**Consequence**: A private, written warning from community leaders, providing
+clarity around the nature of the violation and an explanation of why the
+behavior was inappropriate. A public apology may be requested.
+
+2. Warning
+~~~~~~~~~~
+**Community Impact**: A violation through a single incident or series of
+actions.
+
+**Consequence**: A warning with consequences for continued behavior. No
+interaction with the people involved, including unsolicited interaction with
+those enforcing the Code of Conduct, for a specified period of time. This
+includes avoiding interactions in community spaces as well as external channels
+like social media. Violating these terms may lead to a temporary or permanent
+ban.
+
+3. Temporary Ban
+~~~~~~~~~~~~~~~~
+**Community Impact**: A serious violation of community standards, including
+sustained inappropriate behavior.
+
+**Consequence**: A temporary ban from any sort of interaction or public
+communication with the community for a specified period of time. No public or
+private interaction with the people involved, including unsolicited interaction
+with those enforcing the Code of Conduct, is allowed during this period.
+Violating these terms may lead to a permanent ban.
+
+4. Permanent Ban
+~~~~~~~~~~~~~~~~
+**Community Impact**: Demonstrating a pattern of violation of community
+standards, including sustained inappropriate behavior, harassment of an
+individual, or aggression toward or disparagement of classes of individuals.
+
+**Consequence**: A permanent ban from any sort of public interaction within the
+community.
+
+Attribution
+-----------
+This Code of Conduct is adapted from the `Contributor Covenant <https://www.contributor-covenant.org>`_,
+version 2.1, available at
+`https://www.contributor-covenant.org/version/2/1/code_of_conduct.html <https://www.contributor-covenant.org/version/2/1/code_of_conduct.html>`_.
+
+Community Impact Guidelines were inspired by
+`Mozilla's code of conduct enforcement ladder <https://github.com/mozilla/diversity>`_.
+
+For answers to common questions about this code of conduct, see the FAQ at
+`https://www.contributor-covenant.org/faq <https://www.contributor-covenant.org/faq>`_. Translations are available at
+`https://www.contributor-covenant.org/translations <https://www.contributor-covenant.org/translations>`_.

doc/about/roadmap.rst

@@ -0,0 +1,165 @@
+.. _roadmap:
+
+Roadmap
+=======
+
+This page contains the current roadmap for the Vega-Altair project. The roadmap is
+informed by the needs of the Vega-Altair community, and the priorities of the active
+project contributors. It's designed to communicate the direction of the project,
+but it's not a commitment that these items will be completed in a particular timeframe.
+If you would like to help contribute to any of these areas, or suggest new ones,
+please `start a discussion <https://github.com/altair-viz/altair/discussions>`_.
+
+Vega-Altair is deeply integrated with other components in the Vega ecosystem,
+and as such many items on the roadmap will require work in other projects.
+Abbreviations for these projects are included at the end of project descriptions
+where relevant:
+
+* *(VL)* — `Vega-Lite <https://vega.github.io/vega-lite/>`_
+* *(VG)* — `Vega <https://vega.github.io/vega/>`_
+* *(VF)* — `VegaFusion <https://vegafusion.io/>`_
+* *(VC)* — `VlConvert <https://github.com/vega/vl-convert>`_
+
+API Ergonomics
+--------------
+The primary job of the Vega-Altair library is to provide an ergonomic Python
+API for generating Vega-Lite JSON specifications, and there are several improvements
+here that we would like to investigate.
+
+Areas of focus:
+
+* Improve the syntax for creating condition expressions with two or more
+  predicates.
+
+* Explore the possibility of a new operator, ``*``, for modular compositing of sub components.
+  See this composition proposal
+  `queryverse/VegaLite.jl#411 <https://github.com/queryverse/VegaLite.jl/pull/411>`_ and
+  also https://aog.makie.org/stable/generated/penguins/#Tutorial.
+
+* Standardize the API of methods that convert charts into other formats (``alt.Chart().to_<format>``).
+
+* Add type hints to the public API and most of the internals so that users can type check their Altair
+  code with a static type  checker such as mypy. This will also make it easier for other packages to
+  integrate with Altair.
+
+Documentation
+-------------
+We want to continue to improve Vega-Altair's official documentation to be more
+useful for both beginning and experienced users.
+
+Areas of focus:
+
+* Incorporate a conceptual guide that includes best practices of effective
+  data communication.
+
+* Update and extend the tutorial section and replace outdated materials.
+
+* Add usage guide with best practices for publishing Vega-Altair charts in various
+  contexts including websites, research papers, embedded dashboards, and interactive
+  platforms.
+
+* Add guide on building domain specific visualization packages on top of Vega-Altair.
+  For example, Vega-Altair for soccer analytics.
+
+* Add documentation for the expression language that is available throughout the API.
+
+Ecosystem Integration
+---------------------
+We want Vega-Altair to be well integrated with the PyData ecosystem. It should
+work well with popular libraries and ecosystem standards.
+
+Areas of focus:
+
+* Provide integration with the broader Python DataFrame ecosystem (beyond pandas). Ensure
+  that all of Vega-Altair's features are available to any DataFrame library that implements the
+  `DataFrame Interchange Protocol <https://data-apis.org/dataframe-protocol/latest/index.html>`_.
+
+* Work with dashboard toolkit maintainers to ensure that Vega-Altair is well supported.
+  Write documentation for best practices for making Vega-Altair's interactive features
+  available in Python.
+
+Gridded Data Support
+--------------------
+Vega-Altair currently requires tidy tabular data as input, so it is not currently a natural
+choice for working with gridded data. We would like to extend the project to include native
+support for gridded datasets.
+
+Areas of focus:
+
+* Add support for Python array/tensor interchange protocol (through the ``__dlpack__`` interface)
+
+* Add support for creating charts from Xarray
+  `DataArray <https://docs.xarray.dev/en/stable/generated/xarray.DataArray.html>`_
+  objects (rendering large arrays may require the performance work described elsewhere).
+
+Increased Coverage of Statistical Charts
+----------------------------------------
+While Vega-Altair includes support for many types of statistical visualizations,
+there are a few important types that are not yet possible.
+
+Areas of focus:
+
+* Add support for 2D density visualizations
+  (`vega-lite#6043 <https://github.com/vega/vega-lite/issues/6043>`_) *(VL)*
+
+* Add Violin chart support
+  (`vega-lite#3442 <https://github.com/vega/vega-lite/issues/3442>`_) *(VL)*
+
+Map Tile Support
+----------------
+We want Vega-Altair to provide first-class support for displaying map tiles from
+xyz tile providers like OpenStreetMap. Early development is in progress in the
+`altair_tiles <https://github.com/altair-viz/altair_tiles>`_ repository.
+
+Scale/Performance Improvements
+------------------------------
+In the traditional Vega-Altair architecture, a chart's entire input dataset is serialized
+to JSON and transferred to the browser for data transformation and rendering. Rendering
+itself is then performed by The Vega JavaScript library using the Canvas API (which is
+not GPU accelerated). This architecture has many advantages (e.g. chart specifications
+are fully self-contained and portable to Python-free rendering environments), but it
+is not well suited for creating charts of large datasets.
+
+Through a variety of enhancements, our goal is to allow all Vega-Altair charts to
+scale comfortably to over 1 million rows.
+
+Areas of focus:
+
+* Provide optional integration with VegaFusion to automatically
+  move data transformation steps from the browser to efficient multi-threaded implementations
+  in the Python kernel.
+
+* Utilize binary serialization of datasets in Apache Arrow IPC format between the Python kernel
+  and the browser. This will significant reduce serialization time for large unaggregated
+  visualizations such as scatter plots.
+
+* Support creating Vega-Altair charts that reference tables in external database systems, and convert
+  data transformation steps to SQL that can be evaluated by the database before the results are
+  transferred to the Python kernel *(VF)*.
+
+* Add support for GPU accelerated rendering. This will enable rendering of large unnagregated
+  visualizations at interactive speeds. For example, pan and zoom interactions on a large scatter
+  plot *(VG)*.
+
+Static Image Export
+-------------------
+Even though Vega-Altair charts are rendered by the Vega JavaScript library, it's important to
+provide reliable (and easy to install) support for exporting charts to static images. Image
+export was dramatically simplified in Vega-Altair 5.0 with the adoption of VlConvert,
+which has no external dependencies on a system web-browser or Node.js installation. Now that
+image export is easy to install and easy to use, we want to improve support for publication
+workflows.
+
+Areas of focus:
+
+* Support configurable pixel density in PNG image export *(VC)*.
+
+* Support exporting charts to vector PDF files with embedded text *(VC)*.
+
+.. toctree::
+   :maxdepth: 1
+   :caption: About
+   :hidden:
+
+   self
+   code_of_conduct

doc/getting_started/overview.rst

@@ -51,4 +51,5 @@ This documentation serves as the main reference for learning about Altair. Addit
    installation
    starting
    getting_help
+   resources
    project_philosophy

doc/user_guide/ecosystem.rst → doc/getting_started/resources.rst

@@ -1,4 +1,4 @@
-.. _ecosystem:
+.. _resources:
 
 Resources
 =========

doc/index.rst

@@ -59,8 +59,8 @@ Vega-Altair: Declarative Visualization in Python
    User Guide <user_guide/data>
    Examples <gallery/index>
    API <user_guide/api>
-   user_guide/ecosystem
    releases/changes
+   About <about/roadmap>
 
 .. _GitHub: http://github.com/altair-viz/altair
 .. _Git Issues: http://github.com/altair-viz/altair/issues