How to check if a module is installed in Python and, if not, install it within the code?

Question

I would like to install the modules \'mutagen\' and \'gTTS\' for my code, but I want to have it so it will install the modules on every computer that doesn\'t have them, but it

Answer 1

If you want to know if a package installed, you can check it in your terminal using the next command:

pip list | grep <module_name_you_want_to_check>

How this works:

pip list

lists all modules installed in your Python.

The vertical bar | is commonly referred to as a "pipe". It is used to pipe one command into another. That is, it directs the output from the first command into the input for the second command.

grep <module_name_you_want_to_check>

find the keyword from the list.

Example:

pip list| grep quant

Lists all packages which start from "quant" (for example "quantstrats"). If you do not have any output, this means the library is not installed.

Answer 2

You can use the command line :

python -m MyModule

it will say if the module exists

Else you can simply use the best practice :

pip freeze > requirements.txt

That will put the modules you've on you python installation in a file

and :

pip install -r requirements.txt

to load them

It will automatically you purposes

Have fun

Answer 3

You can check if a package is installed using pkg_resources.get_distribution:

import pkg_resources

for package in ['mutagen', 'gTTS']:
    try:
        dist = pkg_resources.get_distribution(package)
        print('{} ({}) is installed'.format(dist.key, dist.version))
    except pkg_resources.DistributionNotFound:
        print('{} is NOT installed'.format(package))

Note: You should not be directly importing the pip module as it is an unsupported use-case of the pip command.

The recommended way of using pip from your program is to execute it using subprocess:

subprocess.check_call([sys.executable, '-m', 'pip', 'install', 'my_package'])

Answer 4

If you would like to preview if a specific package (or some) are installed or not maybe you can use the idle in python. Specifically :

1. Open IDLE
2. Browse to File > Open Module > Some Module
3. IDLE will either display the module or will prompt an error message.

Above is tested with python 3.9.0

Answer 5

EDIT - 2020/02/03

The pip module has updated quite a lot since the time I posted this answer. I've updated the snippet with the proper way to install a missing dependency, which is to use subprocess and pkg_resources, and not pip.

To hide the output, you can redirect the subprocess output to devnull:

import sys
import subprocess
import pkg_resources

required = {'mutagen', 'gTTS'}
installed = {pkg.key for pkg in pkg_resources.working_set}
missing = required - installed

if missing:
    python = sys.executable
    subprocess.check_call([python, '-m', 'pip', 'install', *missing], stdout=subprocess.DEVNULL)

Like @zwer mentioned, the above works, although it is not seen as a proper way of packaging your project. To look at this in better depth, read the the page How to package a Python App.

Answer 6

you can use try/except:

try:
    import time
    print("module 'time' is installed")
except ModuleNotFoundError:
    print("module 'time' is not installed")
    # or
    install("time") # the install function from the question