Introduction to Python Module | Computer Science for Grade 11 PDF Download

Module

• A module is a grouping of functions. The program is divided into different parts under different levels, called modules.
• Also, suppose we have created some functions in a program and we want to reuse them in another program. In that case, we can save those functions under a module and reuse them.
• A module is created as a python (.py) file containing a collection of function definitions.

Import Statement

• To use a module, we need to import the module. Once we import a module, we can directly use all the functions of that module.

The syntax of import statement is as follows:

• import modulename1 [,modulename2, …]

This gives us access to all the functions in the module(s).

• To call a function of a module, the function name should be preceded with the name of the module with a dot(.) as a separator.

The syntax is as shown below:

• modulename.functionname()

Built-in-Module

Python library has many built-in modules that are really handy to programmers. Let us explore some commonly used modules and the frequently used functions that are found in those modules:

• math
• random
• statistics

1. Module name : math

• It contains different types of mathematical functions.
• Most of the functions in this module return a float value.
• In order to use the math module we need to import it using the following statement:

import math
Some of the commonly used functions in math module are given in Table.

2. Module name : random

• This module contains functions that are used for generating random numbers.
• For using this module, we can import it using the following statement:

import random

• Some of the commonly used functions in random module are given in Table.

3. Module name : statistics

• This module provides functions for calculating statistics of numeric (Real-valued) data. It can be included in the program by using the following statements:

import statistics

• Some of the commonly used functions in statistics module are given in Table :-

Important points regarding Import Statement:

• import statement can be written anywhere in the program
• Module must be imported only once.
• In order to get a list of modules available in Python, we can use the following statement: help(“module”)
• To view the content of a module say math, type the following: help(“math”)
• The modules in the standard library can be found in the Lib folder of Python.

From Statement

• Instead of loading all the functions into memory by importing a module, from statement can be used to access only the required functions from a module.
• It loads only the specified function(s) instead of all the functions in a module.

Its syntax is :
from modulename import functionname [,functionname,…]

• To use the function when imported using “from statement” we do not need to precede it with the module name.
• Rather we can directly call the function as shown in the following examples:

Example-

• >>> from random import random
• >>> random() #Function called without the module name

Output:

• 0.9796352504608387

Example –

• >>> from math import ceil, sqrt
• >>> value = ceil(624.7)
• >>> sqrt(value)

Output:

• 25.0

Composition

• A programming statement wherein the functions or expressions are dependent on each other’s execution for achieving an output is termed as composition.

Example :

• >>> sqrt(ceil(624.7))
• >>> sqrt(trunc(625.7))

a = int(input("First number: "))
print("Square root of ",a ," = ",math.sqrt(a))
print(floor(a+(b/c)))
math.sin(float(h)/float(c))

Creating a User Define Module

• In Python standard library, we can also create our own module consisting of our own functions.

Create a user defined module basic_math that contains the following user defined functions:

• To add two numbers and return their sum.
• To subtract two numbers and return their difference.
• To multiply two numbers and return their product.
• To divide two numbers and return their quotient and print “Division by Zero” error if the denominator is zero.
• Also add a docstring to describe the module. After creating module, import and execute functions.

The requirement is:

• Write a docstring describing the module.
• Write user defined functions as per the specification.
• Save the file.
• Import at shell prompt and execute the functions.

Output:

doc variable stores the docstring. To display docstring of a module we need to import the module and type the following:
print(<modulename>._ _doc_ _) #_ _ are 2 underscore without space