setuptools: package data folder location

Option 1: Install as package data

The main advantage of placing data files inside the root of your Python package
is that it lets you avoid worrying about where the files will live on a user’s
system, which may be Windows, Mac, Linux, some mobile platform, or inside an Egg. You can
always find the directory data relative to your Python package root, no matter where or how it is installed.

For example, if I have a project layout like so:

project/
    foo/
        __init__.py
        data/
            resource1/
                foo.txt

You can add a function to __init__.py to locate an absolute path to a data
file:

import os

_ROOT = os.path.abspath(os.path.dirname(__file__))
def get_data(path):
    return os.path.join(_ROOT, 'data', path)

print get_data('resource1/foo.txt')

Outputs:

/Users/pat/project/foo/data/resource1/foo.txt

After the project is installed as an Egg the path to data will change, but the code doesn’t need to change:

/Users/pat/virtenv/foo/lib/python2.6/site-packages/foo-0.0.0-py2.6.egg/foo/data/resource1/foo.txt

---

Option 2: Install to fixed location

The alternative would be to place your data outside the Python package and then
either:

1. Have the location of data passed in via a configuration file,
   command line arguments or
2. Embed the location into your Python code.

This is far less desirable if you plan to distribute your project. If you really want to do this, you can install your data wherever you like on the target system by specifying the destination for each group of files by passing in a list of tuples:

from setuptools import setup
setup(
    ...
    data_files=[
        ('/var/data1', ['data/foo.txt']),
        ('/var/data2', ['data/bar.txt'])
        ]
    )

Updated: Example of a shell function to recursively grep Python files:

atlas% function grep_py { find . -name '*.py' -exec grep -Hn $* {} \; }
atlas% grep_py ": \["
./setup.py:9:    package_data={'foo': ['data/resource1/foo.txt']}