List python packages installed in a directory (such as with pip install --target my_dir)

list-target.py

import sys
import pkg_resources
"""
List python packages installed in a directory (such as with pip install --target my_dir)

  python list-target.py /path/to/my_dir  # can be relative or absolute
"""

try:
    target_dir = sys.argv[1]
except IndexError:
    print('ERROR: Pass the target_dir as an argument. e.g. python list-target.py my_dir')
    exit(1)

print('Looking for packages in {} ...'.format(target_dir))
env = pkg_resources.Environment([target_dir])

dists = []
for project in env:
    for dist in env[project]:
        dists.append("{}=={}".format(dist.project_name, dist.version))

print('\n'.join(sorted(dists)))