[FIXED] How to save a python script into a local directory and call it with an import statement?

Issue

I am brand new to creating modules. I am working with a large Jupyter Lab (JL) file with lots of custom functions. I would like to take those functions, save them in a python file in the same working directory that my JL file is pulling data from, and import them as functions. I don't want to save them to the PIP package manager just yet; I just want to save them as local packages for now.

The functions would be in a .py file in a format similar to this:

def func1(x,y,z):
    """
    x = custom input
    y = custom imput
    z = custom input
    """
    
    do stuff


def func2(x,y,z):
    """
    x = custom input
    y = custom imput
    z = custom input
    """
    
    do stuff

def func3(x,y,z):
    """
    x = custom input
    y = custom imput
    z = custom input
    """
    
    do stuff

def func4(x,y,z):
    """
    x = custom input
    y = custom imput
    z = custom input
    """
    
    do stuff

I would save this in a python file such as "custom_func.py" and save it in the same directory as my JL file.

After saving the python file, what do I need to do so that I can import this as a custom local package? I have seen that you need to do something with __init__.py, but I'm just not sure what that is.

Solution

After saving the python file, what do I need to do so that I can import this as a custom local package?

You don't have to do anything else. You can bring the function into your namespace from the script "custom_func.py" into the JupyterLab notebook.
Did you try:

from custom_func import func1, func2, func3, func4

Now you can use each of those functions in your notebook as if they had been written in your notebook. For example, result = func4(5,6,7).

Or alternatively, you can bring in the entire custom_func script and call it by reference to the name of the imported file followed by a dot followed by the function, like module_name.function_name:

import custom_func
my_result = custom_func.func1(1,2,3)

I just adapted something like here to your example. You may want to look over that post as it may give you other options you prefer. The same things works in a script as well, which is what that post was about.

---

One of the reasons you may want to limit what you bring in is so you don't clobber what you have in your namespace already. Imagine you already had a func3 defined. If you brought in a func3 by the first method I suggested, you'd probably note that was going on and act accordingly. Maybe rename your other function. If you did from custom_func import *, you might not notice you just replaced func3. If you import the second way I suggested, the new functions are under the module name reference, and so that helps eliminate there being two func3. Because one will just be func3 and one is custom_func.func3. However, often the first option I proposed is preferable so that you keep your namespace as clean as possible.

Answered By - Wayne

Answer Checked By - Marie Seifert (PHPFixing Admin)