Transition from MATLAB to Python

Question

I know this question has been asked before but I can't make heads or tails of what the answer means.

I am making the transition from MATLAB to Python. In MATLAB I can write my own functions and use them in my code. I know I can do the same thing in Python. But I am having a hard time figuring out how to do it.

What I would like to do it create a file with multiple function definitions and then import it into Python like any other module.

First, is this the proper way of thinking it about it? Or do I just need to create multiple definition files for each function?

Second, if it is the proper way of thinking about it how do I access the file? I know you have to set the PYTHONPATH. I have looked at it and where it is looking makes no sense to me.

As an Example: I created a folder called User. In it I have a python function called ted.py. I put said file where the rest of the library files are located (as in numpy or scipy). I want to import the file called User. How can I do this?

After working with Python for awhile I get it. As long as the file is in the same directory and you use the import properly you can use one , some or all of the function definitions in the file.

yes, you are in right track. Every `py` file can be imported as a module. Just write `from filename import functionName` and you are done. — Ahsanul Haque, Oct 17 '15 at 18:33
You can also `import sys; sys.path.append('dirname')` to add `dirname` to your python path for importing. — Andras Deak -- Слава Україні, Oct 17 '15 at 18:41
Neither of these works. No matter what I do it keeps telling me that the directory does not exist. — Jay, Oct 17 '15 at 21:00
Ok, I can install individual .py files. But if I want to install all the files in a folder is what I am having a problem with. — Jay, Oct 17 '15 at 21:17

score 0 · Accepted Answer · edited May 23 '17 at 12:01

You have an un-matlab-like (matlab-unlike? dis-matlab-like?) option of putting multiple function definitions into the same .py file. Once the file -- say, fundefs.py -- is on your path, possibly through having issued import sys; sys.path.append('path/to/fundefs');, you can import it

through import fundefs, after which you can access the functions therein by fundefs.fun1, fundefs.fun2 etc.
through from fundefs import *, which will throw all the functions into your current namespace. This is generally discouraged (and frowned upon) for larger modules as it will pollute your namespace, but for a few functions of your own this might just be what you're after. See also this very informative answer (and also comments therein).
as a middle ground through import very_long_and_descriptive_module_name as shorthand to access your functions as shorthand.fun1, shorthand.fun2 etc. (in the obvious case if your definitions are in the file very_long_and_descriptive_module_name.py)

score 0 · Answer 2 · answered Oct 17 '15 at 23:19

0

You don't import User. What you want is to import ted. Typically, you would put ted.py in the same folder as your main python file, not in a separate folder.

answered Oct 17 '15 at 23:19

saulspatz

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Transition from MATLAB to Python

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