Wsrtjtyk

Apologies if this is a very stupid question but I am new to python and although I have done some googling I cannot think how to phrase my search query.

I am writing a python script that relies on some libraries (pandas, numpy and others). At some point in the future I will be passing this script onto my University so they can mark it etc. I am fairly confident that the lecturer will have python installed on their PC but I cannot be sure they will have the relevant libraries.

I have included a comments section at the top of the script outlining the install instructions for each library but is there a better way of doing this so I can be sure the script will work regardless of what libraries they have?

An example of my script header

############### - Instructions on how to import libraries - ###############



#using pip install openpyxl using the command - pip install openpyxl



#########################################################################



import openpyxl

import random

import datetime

You can firstly make sure that the respective library is installed or not by using try | except, like so:

try:

    import numpy

except ImportError:

    print('Numpy is not installed, install now to continue')

    exit()

Now, if numpy is installed in his computer, then system will just import numpy and will move on, but if Numpy is not installed, then the system will exit python logging the information required, i.e., x is not installed.

And implement the exact same for each and every library you are using.

But if you want to directly install the library which is not installed, you can use this:

Note: Installing libraries silently is not a recommended way.

import os



try:

    import numpy

except ImportError:

    print('Numpy is not installed, installing now......')

    resultCode = os.system('pip install numpy')



    if resultCode == 0:

        print('Numpy installed!')

        import numpy

    else:

        print('Error occured while installing numpy')

        exit()

Here, if numpy is already installed, then the system will simply move on after installing that, but if that is not installed, then the system will firstly install that and then will import that.

Distributing code is a huge chapter where you can invest enormous amounts of time in order to get things right, according to the current best practices and what not. I think there is different degrees of rightness to solutions to your problem, with more rightness meaning more work. So you have to pick the degree you are comfortable with and are good to go.

The best route

Python supports packaging, and the safest way to distribute code is to package it. This allows you to specify requirements in a way that installing your code will automatically install all dependencies as well.

You can use existing cookiecutters, which are project-templates, to create the base you need to build packages:

pip install cookiecutter

cookiecutter https://github.com/audreyr/cookiecutter-pypackage

Running this, and answering the ensuing questions, will leave you with python code that can be packaged. You can add the packages you need to the setup.py file:

requirements = ['openpyxl']

Then you add your script under the source directory and build the package with:

pip wheel .

Let's say you called your project my_script, you got yourself a fresh my_script-0.1.0-py2.py3-none-any.wheel file that you can send to your lecturer. When they install it with pip, openpyxl will be automatically installed in case it isn't already.

Unfortunately, if they should also be able to execute your code you are not done yet. You need to add a __main__.py file to the my_script folder before packaging it, in which you import and execute the parts of your code that are runnable:

my_script/my_script/__main__.py:

from . import runnable_script



if __name__ == '__main__':

    runnable_script.run()

The installed package can then be run as a module with python -m my_script

The next best route

If you really only have a single file and want to communicate to your lecturer which requirements are needed to run the script, send them both your script and a file called requirements.txt, which contains the following lines:

openpyxl

.. and that's it. If there are other requirements, put them on separate lines. If the lecturer has spent any amount of time working with python, they should know that running pip install -r requirements.txt will install the requirements needed to run the code you have submitted.

The if-you-really-have-to route

If all your lecturer knows how to do is entering python and then the name of your script, use DudeCoders approach. But be aware that silently installing requirements without even interactive prompts to the user is a huge no-no in the software-engineering world. If you plan to work in programming you should start with good practices rather sooner than later.