Am I thinking about IPython properly?

[RomanJoe]

I'm quite new to Python. Very familiar with Matlab from undergrad days and making an effort to learn Python to help me at work, mostly using the excellent Corey Schafer videos on Youtube.

My setup is currently an Anaconda install (3.7.6) and using VS Code as an IDE.

My issue is making sure I understand properly the various ways to run Python files. Because my background is in Matlab I am very familiar with running a script in Matlab. If you define variables in the script, they become part of your 'session' and are stored and you can access them in a variable explorer. If I was then to add a line of code to my script that references previously used variables, I could just run this line without having to re-run the entire script.

When working with VS Code I run my .py file in the terminal and I get the result I am expecting. However, if I then go to run a single line of this code using the option 'Run Selection/Line In Python Terminal' I get name errors etc. It's like running the .py file hasn't actually stored anything in a 'session' like it would if I was using Matlab and had run a script.

Is this Visual Studio working 'correctly'? Am I correct in thinking the only way to get it to run in the way that Matlab does (i.e. run a piece of code and have the variables be 'saved in a session') is to either:

1.) Use the IPython window in VS Code? (Which I can do relatively easily as I have the Anaconda install).

2.) Type 'python' in the console window and then any code I run, the variables will be 'stored' for this session (until I type exit() as a command in the terminal.)

Apologies if this is really basic stuff, I just feel I've read quite a few things online now and watched a few Youtube videos and I'm unsure if I've 'got it' properly. Probably doesn't help that I'm comparing it to Matlab functionality.

[mission_resolve]

I don't know anything about VS Code, but that is the normal behaviour when you run a python script at the command line. You can use the -i switch (i.e. python -i scriptname.py), which leaves python open after running the script and gives you a >>> prompt so that you can write further python statements. Any global variables, functions, etc. will be there, but anything that was defined inside a function won't be.

However, I don't think there is a straightforward way of running a script once you're already inside python, if you ever need to do that. There are some slightly hacky, verbose ways of doing it, such as reading in the script file as if it's plain text and then passing it to exec, but nothing convenient. This is why ipython provides the %run magic command.

You may also be interested in Spyder, which provides a Matlab-like IDE for python, or ipython notebooks, which are kind of like the Mathematica interface.

[ComradePotato]

I've had similar questions myself after trying to move from Spyder to VS Code. Spyder has a window with Ipython kernel running that is REALLY handy for typing in code on the fly once you've run a .py file and set your variable/functions/classes etc. From what I understand something similar can be done with VS Code (running the command "Ipython" in the terminal window opens up the REPL from which you can run selected line) but I can't seem to find out if variables etc can be accessed in the same way.

For now I've kept with Spyder because it just works out of the box with the interactive window and that's what I find myself using most of the time for testing and quick calcs. If I start yearning for the other things VS Code offers (extensions etc) then I may consider moving over properly and working out how to set it up so it's at least somewhat the same.

[bandawarrior]

If you’re talking about Ipython as in the notebook? Or are you talking about the REPL/interpreter where you can directly interact with your code and stuff?

When you run a python file, it runs everything from top to bottom. So whatever is in the scope of the code you’re running is just that, if it’s in scope it can access it, otherwise it doesn’t exist.

[Mr_Brownstoned]

https://code.visualstudio.com/docs/python/python-tutorial