Check if module exists, if not install it

Question

I want to check if a module exists, if it doesn\'t I want to install it.

How should I do this?

So far I have this code which correctly prints f

Answer 1

This approach of dynamic import work really well in cases you just want to print a message if module is not installed. Automatically installing a module SHOULDN'T be done like issuing pip via subprocess. That's why we have setuptools (or distribute).

We have some great tutorials on packaging, and the task of dependencies detection/installation is as simple as providing install_requires=[ 'FancyDependency', 'otherFancy>=1.0' ]. That's just it!

But, if you really NEED to do by hand, you can use setuptools to help you.

from pkg_resources import WorkingSet , DistributionNotFound
working_set = WorkingSet()

# Printing all installed modules
print tuple(working_set)

# Detecting if module is installed
try:
    dep = working_set.require('paramiko>=1.0')
except DistributionNotFound:
    pass

# Installing it (anyone knows a better way?)
from setuptools.command.easy_install import main as install
install(['django>=1.2'])

Answer 2

You can use os.system as follows:

import os

package = "package_name"

try:
    __import__package
except:
    os.system("pip install "+ package)