Python Day - 8 Modules-Meaning and Types,Tasks

Modules:

1. Every python file is a module.Files which we save with the extension(.py) all are modules.
2. Modules can be reused using import function-It helps to import one module to another module.

Special variables:
Denoted by "__"-Double underscore(in python it is called as dunder) in front and backside of a variable.

Example:1
Input:

print("Hello")
print(__name__)
print(__file__)

Output:

Hello
__main__
/home/guru/Desktop/Guru/Bank.py

In the above example,
---> name is used to find whether we are working in same module or from different module.If we are working in same module then main will be the output which means in same working module we are printing.Incase if we are printing it in another module by importing then the output will be that module name.
--->file is used for locating the module.

Example:2
To prove module is reusable:

Case:1 Both the python modules are in same folder

Input:

calculator.py-module1

def add(no1,no2):
    print(no1+no2)

def subtract(no1,no2):
    print(no1-no2)


def multiply(no1,no2):
    print(no1*no2)

def divide(no1,no2):
    print(no1/no2)

user.py-module2

import calculator

calculator.add(10,3)
calculator.multiply(10,3)

So we have imported from calculator.py to user.py and calling a function in module 2.
Output will be

13
30

Case:2 Python modules in different folders

If both modules are in different folders then the output will show modulenotfounderror.

Output:

ModuleNotFoundError: No module named 'calculator'

If we need specific functions alone from calculator.py means then no need to import whole module,instead we can use "from" to take specific function

from calculator import add, divide

add(10,3)
divide(10,2)

doc-->Documentation string
This variable is used to know about the particular module,like a description.
For every module ther will be a documentation which will be mentioned in ''' ''' or """ """.

'''It is about special variables'''

print(__doc__)

Output:

It is about special variables

help-To see all details about the particular module like functions,file location, including documentation string.

#In user.py module:

import calculator

print(help(calculator))

Note:vi (module name.py) -is used to open the file in terminal itself instead of opening text editor.And after saving if we reload in text editor changes will be reflecting in it.

Type of modules:
userdefined-Whatever module we create with extension .py is userdefined modules.

predefined modules-Modules which are inbuilt in python.
help('modules') using this we can view all predefined modules in python.

Otp generator: Using random module:

import random
otp = random.randint(100000,999999)
print(otp)

Output:

263861
696781
802686

Task 1:

1. Create a python module called Bank.
2. Add functions: deposit(amount), withdraw(amount)
3. Create one more python module called Customer
4. From customer module, call deposit and withdraw functions of Bank module.

Bank.py:module 1

def deposit(amount):
    print("Total deposit amount is ",amount)
    return(amount)

def withdraw(amount):
    print("Total withdrawal amount is ",amount)
    return(amount)

customer.py:module 2

import Bank

total_deposit=Bank.deposit(100000)
total_withdrawal=Bank.withdraw(20000)

print("Bank balance is ",(total_deposit-total_withdrawal))

Output will be

Total deposit amount is  100000
Total withdrawal amount is  20000
Bank balance is  80000

Task:2
Few important predefined modules:

1) Os module:It is used for interacting with our operating system.

import os
print("Contents:", os.listdir())

output:

Contents: ['user.py', 'Bank.py', '__pycache__', 'calculator.py', 'customer.py', 'hello.py', 'python classes']

2) math: Performs mathematical operations.

Ex:Calculate square root

import math
print("Square Root of 16:", math.sqrt(16))

Output:

Square Root of 16: 4.0

3) datetime: Manages dates and times.

from datetime import datetime

now = datetime.now()
print("Current Date and Time:", now)

Output:

Current Date and Time: 2024-11-22 10:54:46.494016

4) sys - System-Specific Parameters and Functions:Provides access to system-specific parameters.

import sys

print("Python Version:", sys.version)

output:Displays python version

Python Version: 3.12.3 (main, Nov  6 2024, 18:32:19) [GCC 13.2.0]

5) re - Regular Expressions: Allows for pattern matching in strings.
If any string repeats and need to find that alone we can use re module.

import re

text = "cow cat cow dog"
matches = re.findall(r"cow", text)
print("Matches:", matches)

Output:

Matches: ['cow', 'cow']

6) collections - Specialized Data Structures: Provides high-performance container datatypes.

from collections import Counter

data = ['a', 'b', 'a', 'c', 'b', 'a']
count = Counter(data)
print("Occurrences:", count)

Output: From the above input output will count the occurances of each data and displays.

Occurrences: Counter({'a': 3, 'b': 2, 'c': 1})

7) Django: Used to create web applications.

8) String: provides a collection of constants and functions that make it easier to work with strings.

Ex:#using one of the constants-string.ascii_lowercase

import string

print("Lowercase Letters:", string.ascii_lowercase)

output:

Lowercase Letters: abcdefghijklmnopqrstuvwxyz