When I do a pip freeze I see large number of Python packages that I didn't explicitly install, e.g.
$ pip freeze
Cheetah==2.4.3
GnuPGInterface==0.3.2
Landscape-Client==11.01
M2Crypto==0.20.1
PAM==0.4.2
PIL==1.1.7
PyYAML==3.09
Twisted-Core==10.2.0
Twisted-Web==10.2.0
(etc.)
Is there a way for me to determine why pip installed these particular dependent packages? In other words, how do I determine the parent package that had these packages as dependencies?
For example, I might want to use Twisted and I don't want to depend on a package until I know more about not accidentally uninstalling it or upgrading it.
You could try pipdeptree, which displays dependencies as a tree structure e.g.:
$ pipdeptree
Lookupy==0.1
wsgiref==0.1.2
argparse==1.2.1
psycopg2==2.5.2
Flask-Script==0.6.6
- Flask [installed: 0.10.1]
- Werkzeug [required: >=0.7, installed: 0.9.4]
- Jinja2 [required: >=2.4, installed: 2.7.2]
- MarkupSafe [installed: 0.18]
- itsdangerous [required: >=0.21, installed: 0.23]
alembic==0.6.2
- SQLAlchemy [required: >=0.7.3, installed: 0.9.1]
- Mako [installed: 0.9.1]
- MarkupSafe [required: >=0.9.2, installed: 0.18]
ipython==2.0.0
slugify==0.0.1
redis==2.9.1
To install it, run:
pip install pipdeptree
As noted by @Esteban in the comments you can also list the tree in reverse with -r or for a single package with -p <package_name>. So to find which module(s) Werkzeug is a dependency for, you could run:
$ pipdeptree -r -p Werkzeug
Werkzeug==0.11.15
- Flask==0.12 [requires: Werkzeug>=0.7]