How to Import a File in Python

To import a file in Python, you can use the import statement, which makes the module’s contents available in your current script. The import statement combines two operations; it searches for the named module, then binds the search results to a name in the local scope.

For example, if you want to create a random number, you need to import the random package using “import random“; if you’re going to access the file system, you will use the OS package.

Python can put definitions in one file and use them in the script or an interactive instance of the interpreter. Such a file is called the module; definitions from a module can be imported into other modules or the main module (the collection of variables you can access in the script executed at the top level and in calculator mode).

The file name is a module name with the suffix .py appended. The module’s name (as a string) is available as the value of the global variable __name__.

For example, create a new file called sum.py and add the following code inside the file.

def add(a, b):
  c = a + b
  return c

The sum.py file has one function called add(), which takes two parameters and returns the sum of the provided arguments.

The sum.py file is a module in the above file, and add() is its method.

We can import the sum module using the “import sum” inside the other file. But first, let’s import the app.py file, which is in the same directory as the sum.py file.

# app.py

import sum

So, the import syntax is the following.

Python import syntax

import modulename

In our example, modulename = sum.

Now, we can use the add() function of the sum module.

# app.py

import sum

print(sum.add(3, 4))

Output

7

If you intend to use the add() function more than once in your file, you can assign it to a local name.

# app.py

import sum

summation = sum.add
print(summation(3, 4))

Output

7

In the above code, we have assigned the sum() function to summation the local name and then use it anywhere in the file.

More on Import Modules

Python modules can contain executable statements as well as function definitions. These statements are intended to initialize the module. Modules are executed only for the first time the module name is encountered in the import statement.

Python modules can import other modules. It is good practice but not required to place all the import statements at the beginning of a file or module (or script). Instead, the imported module names are placed in the importing module’s global symbol table, which Python tracks precisely.

Some variants of the import statement import names from the module directly into the importing module’s symbol table.

For instance, see the following code.

from sum import add

print(add(3, 4))

Output

7

You will get the same output.

This does not introduce the module name from which the imports are taken in the local symbol table (so the sum is not defined).

There is even a variant to import all names that a module defines.

from sum import *

print(add(3, 4))

Output

7

This imports all names except those beginning with an underscore (_).

So, these are the ways to import a file in Python.

That’s it.

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