Get detailed dependency information from site packages.

dep_tree.py

from __future__ import print_function
from pprint import pprint as print
import pip

def get_all_package_dependencies():
    """Return dictionary of installed packages to list of package dependencies."""
    return {
        dist.key: [(r.key, r.specs) for r in dist.requires()]
        for dist in pip.get_installed_distributions()
    }

print(get_all_package_dependencies())