Is there any way to show the dependency trees for pip packages?

I have a project with multiple package dependencies, the main requirements being listed in requirements.txt. When I call pip freeze it prints the currently installed packages as plain list. I would prefer to also get their dependency relationships, something like this:

Flask==0.9
    Jinja2==2.7
    Werkzeug==0.8.3

Jinja2==2.7

Werkzeug==0.8.3

Flask-Admin==1.0.6
    Flask==0.9
    Jinja2==2.7
    Werkzeug==0.8.3

The goal is to detect the dependencies of each specific package:

Werkzeug==0.8.3
    Flask==0.9
    Flask-Admin==1.0.6

And insert these into my current requirements.txt. For example, for this input:

Flask==0.9
Flask-Admin==1.0.6
Werkzeug==0.8.3

I would like to get:

Flask==0.9
    Jinja2==2.7
Flask-Admin==1.0.6
Werkzeug==0.8.3

Is there any way show the dependencies of installed pip packages?

Solution

You should take a look at pipdeptree:

$ pip install pipdeptree
$ pipdeptree -fl
Warning!!! Cyclic dependencies found:
------------------------------------------------------------------------
xlwt==0.7.5
ruamel.ext.rtf==0.1.1
xlrd==0.9.3
openpyxl==2.0.4
  - jdcal==1.0
pymongo==2.7.1
reportlab==3.1.8
  - Pillow==2.5.1
  - pip
  - setuptools

It doesn't generate a requirements.txt file as you indicated directly. However the source (255 lines of python code) should be relatively easy to modify to your needs, or alternatively you can (as @MERose indicated is in the pipdeptree 0.3 README ) out use:

pipdeptree --freeze  --warn silence | grep -P '^[\w0-9\-=.]+' > requirements.txt

The 0.5 version of pipdeptree also allows JSON output with the --json option, that is more easily machine parseble, at the expense of being less readable.