How to import other Python files?

Question

How do I import other files in Python?

1. How exactly can I import a specific python file like import file.py?
2. How can I import a folder instead of a specific file?
3. I want to load a Python file dynamically at runtime, based on user input.
4. I want to know how to load just one specific part from the file.

For example, in main.py I have:

from extra import * 

Although this gives me all the definitions in extra.py, when maybe all I want is a single definition:

def gap():
    print
    print

What do I add to the import statement to just get gap from extra.py?

Answer 1

Import doc .. -- Link for reference

The __init__.py files are required to make Python treat the directories as containing packages, this is done to prevent directories with a common name, such as string, from unintentionally hiding valid modules that occur later on the module search path.

__init__.py can just be an empty file, but it can also execute initialization code for the package or set the __all__ variable.

mydir/spam/__init__.py
mydir/spam/module.py
import spam.module
or
from spam import module

Answer 2

from file import function_name  ######## Importing specific function
function_name()                 ######## Calling function

and

import file              ######## Importing whole package
file.function1_name()    ######## Calling function
file.function2_name()    ######## Calling function

Here are the two simple ways I have understood by now and make sure your "file.py" file which you want to import as a library is present in your current directory only.

Answer 3

the best way to import .py files is by way of __init__.py. the simplest thing to do, is to create an empty file named __init__.py in the same directory that your.py file is located.

this post by Mike Grouchy is a great explanation of __init__.py and its use for making, importing, and setting up python packages.

Answer 4

How I import is import the file and use shorthand of it's name.

import DoStuff.py as DS
DS.main()

Don't forget that your importing file MUST BE named with .py extension

Answer 5

I'd like to add this note I don't very clearly elsewhere; inside a module/package, when loading from files, the module/package name must be prefixed with the mymodule. Imagine mymodule being layout like this:

/main.py
/mymodule
    /__init__.py
    /somefile.py
    /otherstuff.py

When loading somefile.py/otherstuff.py from __init__.py the contents should look like:

from mymodule.somefile import somefunc
from mymodule.otherstuff import otherfunc

Answer 6

There are many ways, as listed above, but I find that I just want to import he contents of a file, and don't want to have to write lines and lines and have to import other modules. So, I came up with a way to get the contents of a file, even with the dot syntax (file.property) as opposed to merging the imported file with yours.
First of all, here is my file which I'll import, data.py

    testString= "A string literal to import and test with"

Note: You could use the .txt extension instead.
In mainfile.py, start by opening and getting the contents.

    #!usr/bin/env python3
    Data=open('data.txt','r+').read()

Now you have the contents as a string, but trying to access data.testString will cause an error, as data is an instance of the str class, and even if it does have a property testString it will not do what you expected.
Next, create a class. For instance (pun intended), ImportedFile

    class ImportedFile:

And put this into it (with the appropriate indentation):

    exec(data)

And finally, re-assign data like so:

    data=ImportedFile()

And that's it! Just access like you would for any-other module, typing print(data.testString) will print to the console A string literal to import and test with.
If, however, you want the equivalent of from mod import * just drop the class, instance assignment, and de-dent the exec.

Hope this helps:)
-Benji