Modules

Definition

• A module is a file consisting of python code. It can define functions, classes and variables and can also include runnable code
• Any python file can be referenced as a module
• A file containing python code, for example: test.py is called a module and its name would be test
• Module vs. Function
  • Function: It’s a block of code that can be used or reused by calling it with a keyword.
  • Example: print () is a function
• Module: It’s a .py file that contains a list of functions (it can also contain variables and classes).
  • Example: math.sqrt(a)
  • Where math is a module sqrt( ) is a function

Syntax

import module_name
module_name.function_name(variable)

Purpose

• When the program grows more in the size, there is a need to split into several files for easier maintenance as well as re-usability of the code
• Once the module is imported, functions or variables are referenced or used to the code

Types of Modules

• Built in Module
• Built in modules are written in C and integrated with python interpreter
• Some important python modules are: math, random
• User Defined Module

A module that is defined by the programmer. Any name can be given to a user defined module

Importing Built in Modules

import

It is simplest and most common way to use modules in the code

Example

import math
x = math.sqrt(25)
print("square root of 25 =",x)

Output

('square root of 25 =', 5.0)

from import

It is used to get a specific function in the code instead of complete file

Example

from math import pi
x = pi
print("value of pi is",x)

Output

('value of pi is', 3.141592653589793)

import with renaming

Creating an alias when importing a module using as

Example

import math as m
x = m.pi
print("value of pi is",x)

Output

 ('value of pi is', 3.141592653589793)

import all

To import all names (definitions) from a module using *

Example

from math import *
x = pi
print("value of pi is",x)

Output

('value of pi is', 3.141592653589793)

Creating User defined Module:

Step 1: To create a module, save the code in a file with extension .py

Example

def add(a,b):
    print(a+b)

Step 2: use the module just created using import statement

Example

import MyModule as mm
mm.add(5,1)

Output

6

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