How can you programmatically get a Python package’s list of dependencies?

The standard setup.py has these documented, but I can’t find an easy way to access it from either Python or the command line.

Ideally, I’m looking for something like:

$ pip install somepackage --only-list-deps
kombu>=3.0.8
billiard>=3.3.0.13
boto>=2.26

or:

>>> import package_deps
>>> package = package_deps.find('somepackage')
>>> print package.dependencies
['kombu>=3.0.8', 'billiard>=3.3.0.13', 'boto>=2.26']

Note, I’m not talking about importing a package and finding all referenced modules. While this might find most of the dependent packages, it wouldn’t be able to find the minimum version number required. That’s only stored in the setup.py.

In addition to the pip show [package name] command, there is pipdeptree.

Just do

$ pip install pipdeptree

then run

$ pipdeptree

and it will show you your dependencies in a tree form, e.g.,

flake8==2.5.0
  - mccabe [required: >=0.2.1,<0.4, installed: 0.3.1]
  - pep8 [required: !=1.6.0,>=1.5.7,!=1.6.1,!=1.6.2, installed: 1.5.7]
  - pyflakes [required: >=0.8.1,<1.1, installed: 1.0.0]
ipdb==0.8
  - ipython [required: >=0.10, installed: 1.1.0]

The project is located at https://github.com/naiquevin/pipdeptree, where you will also find usage information.

Try to use show command in pip, for example:

$ pip show tornado
---
Name: tornado
Version: 4.1
Location: *****
Requires: certifi, backports.ssl-match-hostname

Update (retrieve deps with specified version):

from pip._vendor import pkg_resources


_package_name = 'somepackage'
_package = pkg_resources.working_set.by_key[_package_name]

print([str(r) for r in _package.requires()])  # retrieve deps from setup.py

Output: ['kombu>=3.0.8', 
         'billiard>=3.3.0.13', 
         'boto>=2.26']

Quite a few answers here show pip being imported for use in programs. The documentation for pip strongly advises against this usage of pip.

Instead of accessing pkg_resources via the pip import, you can actually just import pkg_resources directly and use the same logic (which is actually one of the suggested solutions in the pip docs linked for anyone wanting to see package meta information programmatically) .

import pkg_resources

_package_name = 'yourpackagename'

def get_dependencies_with_semver_string():
    package = pkg_resources.working_set.by_key[_package_name]
    return [str(r) for r in package.requires()]

If you’re having some trouble finding out exactly what your package name is, the WorkingSet instance returned by pkg_resources.working_set implements __iter__ so you can print all of them and hopefully spot yours in there :)

i.e.

import pkg_resources

def print_all_in_working_set():
    ws = pkg_resources.working_set
    for package_name in ws:
        print(ws)

This works with both python 2 and 3 (though you’ll need to adjust the print statements for python2)

(THIS IS A LEGACY ANSWER AND SHOULD BE AVOIDED FOR MODERN PIP VERSIONS AND LEFT HERE FOR REFERENCE TO OLDER PIP VERSIONS ) Alex’s answer is good (+1). In python:

pip._vendor.pkg_resources.working_set.by_key['twisted'].requires()

should return something like

[Requirement.parse('zope.interface>=3.6.0')]

where twisted is the name of the package, which you can find in the dictionary :

pip._vendor.pkg_resources.WorkingSet().entry_keys

to list them all:

dict = pip._vendor.pkg_resources.WorkingSet().entry_keys
for key in dict:
    for name in dict[key]:
        req =pip._vendor.pkg_resources.working_set.by_key[name].requires()
        print('pkg {} from {} requires {}'.format(name,
                                                  key,
                                                  req))

should give you lists like this:

pkg pyobjc-framework-syncservices from /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/PyObjC requires [Requirement.parse('pyobjc-core>=2.5.1'), Requirement.parse('pyobjc-framework-Cocoa>=2.5.1'), Requirement.parse('pyobjc-framework-CoreData>=2.5.1')]

Use https://libraries.io/. It is a good place to explore dependencies before installing using pip.

Eg. Type google-cloud-storage and search, then you can find the page for the library (https://libraries.io/rubygems/google-cloud-storage). Select the version for which you want to explore the dependencies from the ‘Releases’ (default is the latest), Under ‘Dependencies’ you can find the dependency list and their supported versions.

Try this according to this article in python:

import pip 
installed_packages = pip.get_installed_distributions()
installed_packages_list = sorted(["%s==%s" % (i.key, i.version)
     for i in installed_packages]) 
print(installed_packages_list)

It will show like:

['behave==1.2.4', 'enum34==1.0', 'flask==0.10.1', 'itsdangerous==0.24', 
 'jinja2==2.7.2', 'jsonschema==2.3.0', 'markupsafe==0.23', 'nose==1.3.3', 
 'parse-type==0.3.4', 'parse==1.6.4', 'prettytable==0.7.2', 'requests==2.3.0',
 'six==1.6.1', 'vioozer-metadata==0.1', 'vioozer-users-server==0.1', 
 'werkzeug==0.9.4']