Help wanted: launch application in a docker image

Hello,
I’m a newbie in docker, but I have something I’m not able to understand. Maybe the problem is very simple and I didn’t understand it.

I have to launch another application inside a docker image I got from a website.
My configuration: Ubuntu 18.04.2 (fresh install). My installation for docker works, I’m able to launch docker image.

I want to understand the principle, so I submit below a very simple problem to understand this principle.

  • I want to install a docker image with only an interactive bash;
  • In this bash, I want to be able to use python (2 or 3) – I suppose python is not installed on my system;
  • I want to edit python code in vscode;
  • I want to use numpy in python.

Can someone tells me how to do this or give me a website where I will be able to understand how to do this.

When I watched on internet about answers on this problem, I didn’t find a simple explanation.

This case I ask help for is not my problem (which is more complex than this simple one), but I hope this simple problem will also help other people.

Thanks for all who will be able to answer at this problem.

What i would do, i would write my code locally on the ubuntu, put all the files in a directory, then i will create a python2 container that mounts that directory and executes the code.
And create another container for python3.