# Data Files Support

In the Python ecosystem, the term “data files” is used in various complex scenarios and can have nuanced meanings. For the purposes of this documentation, we define “data files” as non-Python files that are installed alongside Python modules and packages on the user’s machine when they install a distribution via wheel.

These files are typically intended for use at runtime by the package itself or to influence the behavior of other packages or systems.

Old packaging installation methods in the Python ecosystem have traditionally allowed installation of “data files”, which are placed in a platform-specific location. However, the most common use case for data files distributed with a package is for use by the package, usually by including the data files inside the package directory.

Setuptools focuses on this most common type of data files and offers three ways of specifying which files should be included in your packages, as described in the following section.

## Configuration Options

### 1. `include_package_data`

First, you can use the `include_package_data` keyword.

For example, if the package tree looks like this:

    project_root_directory
    ├── setup.py        # and/or setup.cfg, pyproject.toml
    └── src
        └── mypkg
            ├── __init__.py
            ├── data1.rst
            ├── data2.rst
            ├── data1.txt
            └── data2.txt

When at least one of the following conditions are met:

1. These files are included via the MANIFEST.in file, like so:

       include src/mypkg/*.txt
       include src/mypkg/*.rst

2. They are being tracked by a revision control system such as Git, Mercurial or SVN, AND you have configured an appropriate plugin such as setuptools-scm or setuptools-svn. (See the section below on Adding Support for Revision Control Systems for information on how to configure such plugins.)

then all the `.txt` and `.rst` files will be included into the source distribution.

To further include them into the `wheels`, you can use the `include_package_data` keyword:

Note

Added in version v61.0.0: The default value for `tool.setuptools.include-package-data` is `true` when projects are configured via `pyproject.toml`. This behaviour differs from `setup.cfg` and `setup.py` (where `include_package_data` is `False` by default), which was not changed to ensure backwards compatibility with existing projects.

### 2. `package_data`

By default, `include_package_data` considers all non `.py` files found inside the package directory (`src/mypkg` in this case) as data files, and includes those that satisfy (at least) one of the above two conditions into the source distribution, and consequently in the installation of your package. If you want finer-grained control over what files are included, then you can also use the `package_data` keyword. For example, if the package tree looks like this:

    project_root_directory
    ├── setup.py        # and/or setup.cfg, pyproject.toml
    └── src
        └── mypkg
            ├── __init__.py
            ├── data1.rst
            ├── data2.rst
            ├── data1.txt
            └── data2.txt

then you can use the following configuration to capture the `.txt` and `.rst` files as data files:

The `package_data` argument is a dictionary that maps from package names to lists of glob patterns. Note that the data files specified using the `package_data` option neither require to be included within a MANIFEST.in file, nor require to be added by a revision control system plugin.

Note

If your glob patterns use paths, you must use a forward slash (`/`) as the path separator, even if you are on Windows. `setuptools` automatically converts slashes to appropriate platform-specific separators at build time.

Important

Glob patterns do not automatically match dotfiles, i.e., directory or file names starting with a dot (`.`). To include such files, you must explicitly start the pattern with a dot, e.g. `.*` to match `.gitignore`.

If you have multiple top-level packages and a common pattern of data files for all these packages, for example:

    project_root_directory
    ├── setup.py        # and/or setup.cfg, pyproject.toml
    └── src
        ├── mypkg1
        │   ├── data1.rst
        │   ├── data1.txt
        │   └── __init__.py
        └── mypkg2
            ├── data2.txt
            └── __init__.py

Here, both packages `mypkg1` and `mypkg2` share a common pattern of having `.txt` data files. However, only `mypkg1` has `.rst` data files. In such a case, if you want to use the `package_data` option, the following configuration will work:

Notice that if you list patterns in `package_data` under the empty string `""` in `setup.py`, and the asterisk `*` in `setup.cfg` and `pyproject.toml`, these patterns are used to find files in every package. For example, we use `""` or `*` to indicate that the `.txt` files from all packages should be captured as data files. These placeholders are treated as a special case, `setuptools` do not support glob patterns on package names for this configuration (patterns are only supported on the file paths). Also note how we can continue to specify patterns for individual packages, i.e. we specify that `data1.rst` from `mypkg1` alone should be captured as well.

Note

When building an `sdist`, the data files are also drawn from the `package_name.egg-info/SOURCES.txt` file which works as a form of cache. So make sure that this file is removed if `package_data` is updated, before re-building the package.

Attention

In Python any directory is considered a package (even if it does not contain `__init__.py`, see native namespaces packages on PyPUG:guides/packaging-namespace-packages). Therefore, if you are not relying on automatic discovery, you SHOULD ensure that all packages (including the ones that don’t contain any Python files) are included in the `packages` configuration (see Package Discovery and Namespace Packages for more information).

Moreover, it is advisable to use full packages name using the dot notation instead of a nested path, to avoid error prone configurations. Please check section subdirectories below.

### 3. `exclude_package_data`

Sometimes, the `include_package_data` or `package_data` options alone aren’t sufficient to precisely define what files you want included. For example, consider a scenario where you have `include_package_data=True`, and you are using a revision control system with an appropriate plugin. Sometimes developers add directory-specific marker files (such as `.gitignore`, `.gitkeep`, `.gitattributes`, or `.hgignore`), these files are probably being tracked by the revision control system, and therefore by default they will be included when the package is installed.

Supposing you want to prevent these files from being included in the installation (they are not relevant to Python or the package), then you could use the `exclude_package_data` option:

The `exclude_package_data` option is a dictionary mapping package names to lists of wildcard patterns, just like the `package_data` option. And, just as with that option, you can use the empty string key `""` in `setup.py` and the asterisk `*` in `setup.cfg` and `pyproject.toml` to match all top-level packages.

Any files that match these patterns will be excluded from installation, even if they were listed in `package_data` or were included as a result of using `include_package_data`.

### Interplay between these keywords

Meanwhile, to further clarify the interplay between these three keywords, to include certain data file into the source distribution, the following logic condition has to be met:

    MANIFEST.in or (package-data and not exclude-package-data)

In plain language, the file should be either:

1. included in `MANIFEST.in`; or

2. selected by `package-data` AND not excluded by `exclude-package-data`.

To include some data file into the `.whl`:

    (not exclude-package-data) and ((include-package-data and MANIFEST.in) or package-data)

In other words, the file should not be excluded by `exclude-package-data` (highest priority), AND should be either:

1. selected by `package-data`; or

2. selected by `MANIFEST.in` AND use `include-package-data = true`.

### Summary

In summary, the three options allow you to:

`include_package_data`

  Accept all data files and directories matched by MANIFEST.in or added by a plugin.

`package_data`

  Specify additional patterns to match files that may or may not be matched by MANIFEST.in or added by a plugin.

`exclude_package_data`

  Specify patterns for data files and directories that should not be included when a package is installed, even if they would otherwise have been included due to the use of the preceding options.

Note

Due to the way the build process works, a data file that you include in your project and then stop including may be “orphaned” in your project’s build directories, requiring you to manually deleting them. This may also be important for your users and contributors if they track intermediate revisions of your project using Subversion; be sure to let them know when you make changes that remove files from inclusion so they can also manually delete them.

See also troubleshooting information in Caching and Troubleshooting.

## Subdirectory for Data Files

A common pattern is where some (or all) of the data files are placed under a separate subdirectory. For example:

    project_root_directory
    ├── setup.py        # and/or setup.cfg, pyproject.toml
    └── src
        └── mypkg
            ├── data
            │   ├── data1.rst
            │   └── data2.rst
            ├── __init__.py
            ├── data1.txt
            └── data2.txt

Here, the `.rst` files are placed under a `data` subdirectory inside `mypkg`, while the `.txt` files are directly under `mypkg`.

In this case, the recommended approach is to treat `data` as a namespace package (refer PEP 420). This way, you can rely on the same methods described above, using either 2. package_data or 1. include_package_data. For the sake of completeness, we include below configuration examples for the subdirectory structure, but please refer to the detailed information in the previous sections of this document.

With 2. package_data, the configuration might look like this:

In other words, we allow `setuptools` to scan for namespace packages in the `src` directory, which enables the `data` directory to be identified, and then, we separately specify data files for the root package `mypkg`, and the namespace package `data` under the package `mypkg`.

Alternatively, you can also rely on 1. include_package_data. Note that this is the default behaviour in `pyproject.toml`, but you need to manually enable scanning of namespace packages in `setup.cfg` or `setup.py`:

To avoid common mistakes with 1. include_package_data, please ensure MANIFEST.in is properly set or use a revision control system plugin (see Controlling files in the distribution).

## Accessing Data Files at Runtime

Typically, existing programs manipulate a package’s `__file__` attribute in order to find the location of data files. For example, if you have a structure like this:

    project_root_directory
    ├── setup.py        # and/or setup.cfg, pyproject.toml
    └── src
        └── mypkg
            ├── data
            │   └── data1.txt
            ├── __init__.py
            └── foo.py

Then, in `mypkg/foo.py`, you may try something like this in order to access `mypkg/data/data1.txt`:

    import os
    data_path = os.path.join(os.path.dirname(__file__), 'data', 'data1.txt')
    with open(data_path, 'r') as data_file:
         ...

However, this manipulation isn’t compatible with PEP 302-based import hooks, including importing from zip files and Python Eggs. It is strongly recommended that, if you are using data files, you should use `importlib.resources` to access them. In this case, you would do something like this:

    from importlib.resources import files
    data_text = files('mypkg.data').joinpath('data1.txt').read_text()

`importlib.resources` was added to Python 3.7. However, the API illustrated in this code (using `files()`) was added only in Python 3.9, [2] and support for accessing data files via namespace packages was added only in Python 3.10 [3] (the `data` subdirectory is a namespace package under the root package `mypkg`). Therefore, you may find this code to work only in Python 3.10 (and above). For other versions of Python, you are recommended to use the importlib-resources backport which provides the latest version of this library. In this case, the only change that has to be made to the above code is to replace `importlib.resources` with `importlib_resources`, i.e.

    from importlib_resources import files
    ...

See importlib-resources:using for detailed instructions.

Tip

Files inside the package directory should be read-only to avoid a series of common problems (e.g. when multiple users share a common Python installation, when the package is loaded from a zip file, or when multiple instances of a Python application run in parallel).

If your Python package needs to write to a file for shared data or configuration, you can use standard platform/OS-specific system directories, such as `~/.local/config/$appname` or `/usr/share/$appname/$version` (Linux specific) [1]. A common approach is to add a read-only template file to the package directory that is then copied to the correct system directory if no pre-existing file is found.

## Data Files from Plugins and Extensions

You can resort to a native/implicit namespace package (as a container for files) if you want plugins and extensions to your package to contribute with package data files. This way, all files will be listed during runtime when using importlib.resources. Note that, although not strictly guaranteed, mainstream Python package managers, like pip and derived tools, will install files belong to multiple distributions that share a same namespace into the same directory in the file system. This means that the overhead for `importlib.resources` will be minimum.

## Non-Package Data Files

Historically, `setuptools` by way of `easy_install` would encapsulate data files from the distribution into the egg (see the old docs). As eggs are deprecated and pip-based installs fall back to the platform-specific location for installing data files, there is no supported facility to reliably retrieve these resources.

Instead, the PyPA recommends that any data files you wish to be accessible at run time be included inside the package.

[1]

These locations can be discovered with the help of third-party libraries such as platformdirs.

[2]

Reference: https://importlib-resources.readthedocs.io/en/latest/using.html#migrating-from-legacy

[3]

Reference: https://github.com/python/importlib_resources/pull/196#issuecomment-734520374