How to Import File in Python | Import Modules in Python
If you are working in small or large projects, you always need to work with other modules and packages. Some files are you have created, or some of them are the third parties. To use any module in your code, you must make it accessible in your file, and that is why first, you have to import it.
You can’t use anything in Python before it is defined.
Some things are inbuilt, for example, the basic data types (like float, int, boolean, etc.) can be used whenever you need them. But for most of the things, you have to do will need a little more than that. You have to first import it and then you can use its methods and functions.
For example, if you want to create a random number, then you need to import the random package using “import random“; if you’re going to access the file system, then you will use the OS package.
How to Import File in Python
Python language has a way to 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 into the main module (the collection of variables that you have access to in the script executed at the top level and in calculator mode).
The python module is a file containing definitions and statements. To use the module in Python, we have to import module in other files or the files you have to execute.
The file name is a module name with the suffix .py appended. Within the module, 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.
# sum.py 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.
So, in the above file, the sum.py file is a module and add() is its method.
Now, we can import the sum module using the “import sum” inside the other file. Let’s import in 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
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))
If you intend to use add() function more than once in your file, then you can assign it to a local name.
# app.py import sum summation = sum.add print(summation(3, 4))
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 module can contain executable statements as well as the function definitions. These statements are intended to initialize the module.
They 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). The imported module names are placed in the importing module’s global symbol table which Python tracks it precisely.
There are some variants of the import statement that imports names from the module directly into the importing module’s symbol table.
For instance, see the following code.
# app.py from sum import add print(add(3, 4))
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 in the example, the sum is not defined).
There is even the variant to import all names that a module defines.
See the following code.
# app.py from sum import * print(add(3, 4))
This imports all names except those beginning with an underscore (_).
So, these are the ways to import a file in Python. That’s it for this tutorial.