Mesa

Highlights
Mesa 2.3.0 is a big feature release and the last feature release before 3.0.

There are two main new features:
- The experimental cell-centric discrete spaces, as added in 1994. It allows having cells with not only properties but also active behaviors: the `CellAgent`. Its inspired by NetLogo's [patches](https://ccl.northwestern.edu/netlogo/bind/primitive/patches.html) but extend and generalize this concept further.
- Full support for discrete event scheduling, as added in 2066. It allows scheduling events (like Agent actions) at any time, including non-integer timesteps.

There are a lot of other features: The Jupyter visualisation now supports easier way to specify sliders, `NetworkGrid.get_neighbors()` supports a radius, `AgentSet.get()` can retrieve multiple attributes and there are now benchmarks to track Mesa performance during development.

Finally, 2.3.0 stabilizes the `AgentSet` (including `model.agents`), making it the first experimental Mesa feature that is taken out of it's experimental phase.

Install this release with:

pip install --upgrade mesa

The Mesa 2.3.x-series supports Python 3.9 to 3.12. The next major release will require Python 3.10.

What's Changed
🧪 Experimental features
* Add cell-centric discrete spaces (experimental) by Corvince in https://github.com/projectmesa/mesa/pull/1994
🎉 New features added
* Add performance benchmarking scripts by EwoutH in https://github.com/projectmesa/mesa/pull/1979
* feat: Implement Slider class for JupyterViz by rht in https://github.com/projectmesa/mesa/pull/1972
* Stabilize AgentSet by EwoutH in https://github.com/projectmesa/mesa/pull/2065
* Support discrete event scheduling by quaquel in https://github.com/projectmesa/mesa/pull/2066
🛠 Enhancements made
* JupyterViz: Automatically deduce display name from model class by rht in https://github.com/projectmesa/mesa/pull/1975
* Add radius argument to NetworkGrid.get_neighbors() by EwoutH in https://github.com/projectmesa/mesa/pull/1973
* Speedup of Agentset.shuffle by quaquel in https://github.com/projectmesa/mesa/pull/2010
* feat: Let mesa runserver detect server.py as fallback by rht in https://github.com/projectmesa/mesa/pull/2015
* JupyterViz: {Convert make_plot & prepare ColorCard} to become Solara component by rht in https://github.com/projectmesa/mesa/pull/2020
* new feature: AgentSet.get can retrieve one or more then one attribute by quaquel in https://github.com/projectmesa/mesa/pull/2044
* Update CODE_OF_CONDUCT.md to version 2+ of contrib covenant by jackiekazil in https://github.com/projectmesa/mesa/pull/2052
* Improve flocking benchmark by coderbeta1 in https://github.com/projectmesa/mesa/pull/2054
* Remove JupyterViz Altair marker overlap for huge grid size by rht in https://github.com/projectmesa/mesa/pull/2062
* Add tooltip option to Altair chart by FoFFolo in https://github.com/projectmesa/mesa/pull/2082
* feat: Display model seed & allow user to specify it in JupyterViz by rht in https://github.com/projectmesa/mesa/pull/2069
* warn if placing already placed agent by puer-robustus in https://github.com/projectmesa/mesa/pull/2083
🐛 Bugs fixed
* fix: Apply default value to slider by rht in https://github.com/projectmesa/mesa/pull/2016
* fix: Initialize model _steps and _time during __new__ by rht in https://github.com/projectmesa/mesa/pull/2026
* fix: Use model.schedule only when it is not None by rht in https://github.com/projectmesa/mesa/pull/2050
* fix: Remove JupyterViz grid marker overlap for huge grid size by rht in https://github.com/projectmesa/mesa/pull/2049
📜 Documentation improvements
* Improve readability of badges by rht in https://github.com/projectmesa/mesa/pull/2009
* More pythonic implementation of wolf sheep by quaquel in https://github.com/projectmesa/mesa/pull/2011
* Adding super().__init__() to MoneyModel tutorial by sw23 in https://github.com/projectmesa/mesa/pull/2025
* docs: Convert howto.rst -> howto.md via rst2myst by rht in https://github.com/projectmesa/mesa/pull/2033
* docs: Convert best-practices,overview,packages,mesa,index to .md via rst2myst by rht in https://github.com/projectmesa/mesa/pull/2034
* docs: Convert api/*.rst -> api/*.md via rst2myst by rht in https://github.com/projectmesa/mesa/pull/2035
* docs: Rewrite howto.md using ChatGPT for clarity and conciseness by rht in https://github.com/projectmesa/mesa/pull/2037
* docs: Corrected Contributing Guide Link to Ensure Accessibility by sahusiddharth in https://github.com/projectmesa/mesa/pull/2057
* Rename links to internal .rst files to .md by rht in https://github.com/projectmesa/mesa/pull/2058
* docs: improve introductory tutorial by puer-robustus in https://github.com/projectmesa/mesa/pull/2087
🔧 Maintenance
* Quality of Life: Make codecov less meticulous by Corvince in https://github.com/projectmesa/mesa/pull/1966
* Add CI workflow for performance benchmarks by EwoutH in https://github.com/projectmesa/mesa/pull/1983
* tests: Resolve warnings by defining PropertyLayer dtypes by EwoutH in https://github.com/projectmesa/mesa/pull/1987
* benchmarks.yml: Fix PR branch checkout when triggered by comment by EwoutH in https://github.com/projectmesa/mesa/pull/1998
* Quality of life: automatically fix ruff errors by Corvince in https://github.com/projectmesa/mesa/pull/2004
* benchmarks.yml: Run on addition of label instead of comment by EwoutH in https://github.com/projectmesa/mesa/pull/2002
* ci: Move codespell to pre-commit by rht in https://github.com/projectmesa/mesa/pull/2040
* Schelling by coderbeta1 in https://github.com/projectmesa/mesa/pull/2053
* Move ruff lint settings into dedicated section by Corvince in https://github.com/projectmesa/mesa/pull/2073
* ci: Use uv pip for faster build by rht in https://github.com/projectmesa/mesa/pull/2038
* test: Remove place_agent duplicate warnings by rht in https://github.com/projectmesa/mesa/pull/2086
Other changes
* Minor edits to benchmarking code by quaquel in https://github.com/projectmesa/mesa/pull/1985
* build(deps): bump codecov/codecov-action from 3 to 4 by dependabot in https://github.com/projectmesa/mesa/pull/2030
* [pre-commit.ci] pre-commit autoupdate by pre-commit-ci in https://github.com/projectmesa/mesa/pull/2029
* tests: Speed up test_batch_run by rht in https://github.com/projectmesa/mesa/pull/2039
* Update benchmarks.yml by Corvince in https://github.com/projectmesa/mesa/pull/2043
* docs: Convert visualization .rst -> .md via rst2myst by rht in https://github.com/projectmesa/mesa/pull/2036
* docs: Convert CONTRIBUTING .rst -> .md via rst2myst by rht in https://github.com/projectmesa/mesa/pull/2041
* Correct wolf energy gained from eating sheep by JackAtOmenApps in https://github.com/projectmesa/mesa/pull/2048
* feat: Implement Altair version of grid visualization by rht in https://github.com/projectmesa/mesa/pull/1991

New Contributors
* sw23 made their first contribution in https://github.com/projectmesa/mesa/pull/2025
* JackAtOmenApps made their first contribution in https://github.com/projectmesa/mesa/pull/2048
* coderbeta1 made their first contribution in https://github.com/projectmesa/mesa/pull/2054
* sahusiddharth made their first contribution in https://github.com/projectmesa/mesa/pull/2057
* FoFFolo made their first contribution in https://github.com/projectmesa/mesa/pull/2082
* puer-robustus made their first contribution in https://github.com/projectmesa/mesa/pull/2083

**Full Changelog**: https://github.com/projectmesa/mesa/compare/v2.2.4...2.3.0

Mesa 2.3.0-rc1 is pre-release in preparation for 2.3.0 stable. It had the same release notes as 2.3.0.

Highlights
Mesa v2.2.4 is a small but important bugfix release for the 2.2 release series. It fixes an essential bug in where agents weren't shuffled in the `BaseScheduler`, affecting mainly the `RandomActivation` scheduler (effectively making it sequential activation)([2007](https://github.com/projectmesa/mesa/pull/2007)). It also fixes a small behaviour change in `RandomActivationByType.agents_by_type()` ([#1996](https://github.com/projectmesa/mesa/pull/1996)). Furthermore, this release adds an internal clock to the `Model`, which allows to use a Mesa model without a scheduler (using the `AgentSet` API)([#1942](https://github.com/projectmesa/mesa/pull/1942)).

Updating from previous 2.2 releases is highly recommended, especially when using the `RandomActivation` scheduler.

What's Changed
🛠 Enhancements made
* refactor: Remove dependence on model.schedule, add clock to Model by rht in https://github.com/projectmesa/mesa/pull/1942
🐛 Bugs fixed
* Fix AgentSet inplace shuffle (and thus RandomActivation), add tests by EwoutH and quaquel in https://github.com/projectmesa/mesa/pull/2007
* fix: Reverse dict key and value for agents_by_type by rht in https://github.com/projectmesa/mesa/pull/1996

**Full Changelog**: https://github.com/projectmesa/mesa/compare/v2.2.3...v2.2.4

Highlights
Mesa 2.2.3 is a small release with two improvements to the experimental Solara visualisation, on request of one of our contributors. No stable features have changed.

What's Changed
🧪 Experimental features
* solara_viz: Add borders around ContinuousSpace by EwoutH in https://github.com/projectmesa/mesa/pull/1988
🐛 Bugs fixed
* fix: Explicitly specify JupyterViz space view limits by rht in https://github.com/projectmesa/mesa/pull/1984

**Full Changelog**: https://github.com/projectmesa/mesa/compare/v2.2.2...v2.2.3

Highlights

Mesa 2.2.2 is a small bugfix release, for models in which users had defined `Model.agents` (`self.agents` in a Model (sub)class). This is deprecated, but for now allowed. See [1919 (comment)](https://github.com/projectmesa/mesa/discussions/1919#discussioncomment-8141844).

What's Changed
🐛 Bugs fixed
* Allow user models to assign `Model.agents` for now, but add warning by quaquel in [1976](https://github.com/projectmesa/mesa/pull/1976)

**Full Changelog**: https://github.com/projectmesa/mesa/compare/v2.2.1...v2.2.2

Highlights
After the huge 2.2.0 release we are releasing 2.2.1 which addresses a few bugs, unintended behaviors and a performance regression. 1960 makes sure agent addition and removal is handled correct, 1965 fixed an unintended behavior change in `RandomActivationByType.agents_by_type` and 1964 makes sure we're at least as fast as before 2.2.0, if not faster. The [introduction tutorial](https://mesa.readthedocs.io/en/stable/tutorials/intro_tutorial.html) is also extended with #1955.

We highly recommend updating to 2.2.1 if you're using 2.2.0.

What's Changed
🧪 Experimental features
* jupyter_viz: Implement multiline plot by rht in https://github.com/projectmesa/mesa/pull/1941
🛠 Enhancements made
* make mesa runable without some dependencies by Corvince in https://github.com/projectmesa/mesa/pull/1950
* Improve performance of AgentSet and iter_cell_list_contents by Corvince in https://github.com/projectmesa/mesa/pull/1964
🐛 Bugs fixed
* Bugfix in agentset to handle addition and removal correctly by quaquel in https://github.com/projectmesa/mesa/pull/1960
* Make RandomActivationByType.agents_by_type backward compatible by quaquel in https://github.com/projectmesa/mesa/pull/1965
📜 Documentation improvements
* Refer to just Python instead of Python 3 by rht in https://github.com/projectmesa/mesa/pull/1957
* intro tutorial: Analysing model reporters by EwoutH in https://github.com/projectmesa/mesa/pull/1955
🔧 Maintenance
* Migrate from setuptools to hatch by rht in https://github.com/projectmesa/mesa/pull/1882
* ci: Add tests for mesa-examples by rht in https://github.com/projectmesa/mesa/pull/1956
* refactor: Move Matplotlib-specific Solara components to separate file by rht in https://github.com/projectmesa/mesa/pull/1943

**Full Changelog**: https://github.com/projectmesa/mesa/compare/v2.2.0...v2.2.1