Import custom modules in python

Question

I have segmented some code into several files (for better readability) with several dependencies from other standard libraries (numpy, matplotlib).

E.g,

**ploting.py**
import matplitlib.pyplot as plt
import numpy as np
plot something

**calculating1.py**
import numpy as np
some custom calculation functions using numpy routines

**calculating2.py**
import numpy as np
some custom calculation functions using numpy routines

Afterwards in a main.py I am calling the modules has

import numpy as np
from plotting import funcA,funcB,funC
from calculating1 import funcA,funcB,funC
from calculating2 import funcA,funcB,funC

I would like to know if there is any problem having to import matplitlib and numpy in several modules? Is there a way to make these available "globally"?

Additionally, does python have a name for this sort of structure? A .py file calling other modules? A package? if so, does main.py have a particular name?

Answer 1

From the docs:

The first place checked during import search is sys.modules. This mapping serves as a cache of all modules that have been previously imported, including the intermediate paths.

So it's ok to import a module in several files (if you need that module in that file).

A package is is a directory that contains one or more .py files. A file called __init__.py is required to make Python treat directories as packages.