Check pip dependants instead of requires

checkdependents.py

# Invert all requirements: python checkdependents.py
# View specific: python checkdependents.py somepackage

import collections
import sys

import pip

def invert_dependencies_graph(distributions):
    packages = collections.defaultdict(list)

    for distribution in distributions:
        for dependency in distribution.requires():
            packages[dependency.project_name].append(
                distribution.project_name)

    return packages

if __name__ == '__main__':
    packages = invert_dependencies_graph(
        pip.get_installed_distributions())

    try:
        print packages[sys.argv[1]]
    except IndexError:
        for package, dependants in packages.items():
            print package
            for dependant in dependants:
                print '\t', dependant