Python: Difference between revisions
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Once you have picked the Python packages you want, run <code>nix-shell</code> (or <code>nix develop -f shell.nix</code>) to build the Python environment and enter it. Once in the environment Python will be available in your PATH, so you can run eg. <code>python --version</code>. | Once you have picked the Python packages you want, run <code>nix-shell</code> (or <code>nix develop -f shell.nix</code>) to build the Python environment and enter it. Once in the environment Python will be available in your PATH, so you can run eg. <code>python --version</code>. | ||
Note that with NixOS, this method can be used to install packages at the system level, e.g. <syntaxhighlight lang="nix"> | |||
environment.systemPackages = with pkgs; [ | |||
# ... | |||
(python3.withPackages (python-pkgs: with python-pkgs; [ | |||
pandas | |||
requests | |||
])) | |||
]; | |||
</syntaxhighlight> | |||
=== Using Nix shell (new command line) === | |||
nix shell --impure --expr '(import <nixpkgs> {}).python3.withPackages (ps: with ps; [ swh-core swh-scanner ])' | |||
If you don't use the channels any more, you can replace <code><nixpkgs></code> by an instance of the <code>NixOS/nixpkgs</code> repository using its absolute path. | |||
==== Using a Python package not in Nixpkgs ==== | ==== Using a Python package not in Nixpkgs ==== | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
==== Using <code>buildFHSEnv</code> ==== | ==== Using <code>buildFHSEnv</code> (Recommended) ==== | ||
<syntaxhighlight lang="nix"> | <syntaxhighlight lang="nix"> | ||
#!/usr/bin/env nix-shell | #!/usr/bin/env nix-shell | ||
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=== Using uv === | === Using uv === | ||
<blockquote>A single tool to replace <code>pip</code>, <code>pip-tools</code>, <code>pipx</code>, <code>poetry</code>, <code>pyenv</code>, <code>virtualenv</code>, and more.</blockquote>uv is | <blockquote>A single tool to replace <code>pip</code>, <code>pip-tools</code>, <code>pipx</code>, <code>poetry</code>, <code>pyenv</code>, <code>virtualenv</code>, and more.</blockquote> | ||
uv is written in Rust and does ''not'' need Python as a prerequisite. Use the <code>uv</code> command to initialize Python projects, add Python packages, create or update virtual environments (in <code>.venv</code> folders), etc. as [https://docs.astral.sh/uv/concepts/projects/ described in the uv docs]. Use uv's [https://docs.astral.sh/uv/guides/tools/ tool interface] to install and run Python packages that provide a CLI. | |||
As a system package | |||
<syntaxhighlight lang="nix"> | |||
environment.systemPackages = with pkgs; [ | environment.systemPackages = with pkgs; [ | ||
uv | uv | ||
]; | ]; | ||
</syntaxhighlight>or as a home-manager package<syntaxhighlight lang="nix"> | </syntaxhighlight> | ||
or as a home-manager package | |||
<syntaxhighlight lang="nix"> | |||
home.packages = with pkgs; [ | home.packages = with pkgs; [ | ||
uv | uv | ||
]; | ]; | ||
</syntaxhighlight> | </syntaxhighlight> | ||
If you use uv it's recommended that you install the Python versions you need using the <code>uv python install</code> command, e.g. | |||
<syntaxhighlight lang="python"> | |||
uv python install 3.14 --preview --default | |||
</syntaxhighlight> | |||
You may want to set the <code>UV_PYTHON_DOWNLOADS=never</code> environment variable in your shell to stop uv from downloading Python binaries automatically if needed. Setting <code>environment.localBinInPath = true;</code> is highly recommended, because uv will install binaries in <code>~/.local/bin</code>. | |||
=== Using poetry === | === Using poetry === | ||
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To activate an environment you will need a [https://nixos.org/manual/nixpkgs/stable/#sec-fhs-environments FHS environment] e.g.: | To activate an environment you will need a [https://nixos.org/manual/nixpkgs/stable/#sec-fhs-environments FHS environment] e.g.: | ||
<syntaxhighlight lang="console"> | <syntaxhighlight lang="console"> | ||
$ nix-shell -E 'with import <nixpkgs> {}; (pkgs. | $ nix-shell -E 'with import <nixpkgs> {}; (pkgs.buildFHSEnv { name = "fhs"; }).env' | ||
$ eval "$(micromamba shell hook -s bash)" | $ eval "$(micromamba shell hook -s bash)" | ||
$ micromamba activate my-environment | $ micromamba activate my-environment | ||
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{ pkgs ? import <nixpkgs> {}}: | { pkgs ? import <nixpkgs> {}}: | ||
let | let | ||
fhs = pkgs. | fhs = pkgs.buildFHSEnv { | ||
name = "my-fhs-environment"; | name = "my-fhs-environment"; | ||
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let | let | ||
pkgs = import nixpkgs { inherit system; }; | pkgs = import nixpkgs { inherit system; }; | ||
fhs = pkgs. | fhs = pkgs.buildFHSEnv { | ||
name = "pixi-env"; | name = "pixi-env"; | ||
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{ | { | ||
home.packages = [ | home.packages = [ | ||
(pkgs. | (pkgs.buildFHSEnv { | ||
name = "pixi"; | name = "pixi"; | ||
runScript = "pixi"; | runScript = "pixi"; | ||
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You can also set <code>backend : GTK3Agg</code> in your <code>~/.config/matplotlib/matplotlibrc</code> file to avoid having to call <code>matplotlib.use('gtk3agg')</code>. | You can also set <code>backend : GTK3Agg</code> in your <code>~/.config/matplotlib/matplotlibrc</code> file to avoid having to call <code>matplotlib.use('gtk3agg')</code>. | ||
== Debug Build == | |||
See [https://docs.python.org/3/using/configure.html#python-debug-build python wiki on debug build]. | |||
In order to use a CPython interpreter built using <code>--with-pydebug</code> during configure phase, override any of the python packages passing <code>enableDebug = true</code> argument: | |||
<code>pythonDebug = pkgs.python310.override { enableDebug = true; };</code> | |||
== Installing Multiple Versions == | |||
{{Nixpkgs Manual|name={{ic|lib.meta.lowPrio}} and {{ic|lib.meta.highPrio}}|anchor=#function-library-lib.meta.lowPrio}} can be used to install multiple versions without conflicts ({{issue|369997}}): | |||
{{file|/etc/nixos/configuration.nix|nix|3= | |||
environment.systemPackages = with pkgs; [ | |||
python313 | |||
lib.meta.lowPrio python314 | |||
]; | |||
}} | |||
In this case you may run Python 3.13 via {{ic|python}} or {{ic|python3.13}} and Python 3.14 via {{ic|python3.14}}. | |||
{{Note|If you wrapped Python as described in [[#Running_Python_packages_which_requires_compilation_and/or_contains_libraries_precompiled_without_nix]], call {{ic|lib.meta.lowPrio}} and {{ic|lib.meta.highPrio}} for the wrapped Python instead of calling them inside the wrapping.}} | |||
== Performance == | == Performance == | ||