Python Modules

Python has an excellent feature of structuring and organizing the codes. These range from statements and control structures through functions, methods, and classes at the scripts level and modules and packages at the libraries level.

What is Python Module?

A module is a file containing a piece of prewritten code that allows a program to perform a function or task without coding it inside of the program. Python modules are also saved as ".py" extension

Python has special statements to import a module. Generally, a Python program imports the modules at the beginning of the script. Without importing, a program cannot use a module.

We can create modules ourselves or import modules from the PyPI repository using the pip package manager.

Installing 3rd Party Modules in Python

3rd party modules in Python need to be installed before we can import them. We use the pip cli tool to install these 3rd party modules. The basic syntax of the command to install a module is

			

pip install module_name

				

For example, to install the numpy module, we enter the following command in the cmd prompt or terminal

			

pip install numpy

				

We can also specify a particular version of the module we want to install. Like this

			

pip install numpy==1.13.6

				

How to import modules in Python

import statement is used to import a module in a python program. We can import more than modules with the import statement. Like this

			

import numpy      #importing single module
import math, pandas, datetime       #importing multiple modules
print(datetime.datetime.now())
print(math.pow(2,2))

				

Output:

2022-02-28 07:01:15.349078 4.0

Importing only some parts of a module

Sometimes we want one part of the module to be imported into our program. For that we can use the from statement. With from statement we can import only the necessary parts of a module instead of the whole module. For example

			

from math import factorial
print(factorial(5))

				

Output:

120

Renaming an Imported Module

as keyword is used in Python to rename an imported module. For example

			

import datetime as dt
print(dt.datetime.now())

				

Output:

2022-02-28 15:54:27.475613

How to create a module in Python

Creating a module in Python is pretty simple. We have to write the member functions and variables to be included in the module. We then save this code in a .py python file. Then, import the file as we did above using the import statement. For example

We create a file called custom_module_example.py. Then we define a function in the file. Like this

			

def sayhi():
print("Hi")

				

Now, we can import this module into our program by using the import statement. Like this

			

import custom_module_example
custom_module_example.sayhi()

				

Output:

Hi

Python dir() function

The dir() function is used to return all the member functions and attributes of a python object or module(even the user-created ones). We use it like this

			

import custom_module_example
print(dir(custom_module_example))

				

Output:

['__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', 'sayhi']

Some Popular Python Modules

Given below are some of the most commonly used modules in Python

Module Description
datetime Provides functionalities related to handling and representing date and time data
math Provides various mathematical functions
random Provides functions that can generate data randomly
pygame Allows the programmer to create basic games in Python easily
re Provides features like pattern matching and regular expression
numpy Provides multidimensional array, matrices and various methods to operate on them
beautifulsoup4 Provides functions that performs tasks related to web-scraping
matplotlib Allows the programmer to plot mathematical graphs
django Provides various functionalities related to handling backend of a website
requests Provides functions that can send data over http