Python Modules

1. What is a Module

# file: math_utils.py
def add(a, b):
    return a + b

A module is a file containing Python code (functions, variables, classes) that can be imported and reused in other programs.

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2. Importing a Module

import math

print(math.sqrt(25))  # Output: 5.0

The import keyword loads the entire module and accesses its content using dot notation.

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3. Importing Specific Functions from a Module

from math import sqrt, pow

print(sqrt(16))     # Output: 4.0
print(pow(2, 3))    # Output: 8.0

Imports only selected items, reducing namespace clutter.

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4. Renaming a Module using as

import math as m

print(m.pi)     # Output: 3.141592653589793

Useful for improving readability or avoiding name conflicts.

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5. Creating and Using a Custom Module

# file: calculator.py
def multiply(a, b):
    return a * b

# main.py
import calculator

print(calculator.multiply(4, 5))  # Output: 20

Custom modules help organize reusable logic.

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6. Using __name__ in Modules

# file: demo.py
def main():
    print("Main function executed")

if __name__ == "__main__":
    main()

Ensures code runs only when the file is executed directly, not when imported.

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7. Built-in Modules Example

import datetime

today = datetime.date.today()
print(today)

Python provides rich built-in modules like os, sys, math, datetime, and random.

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8. Exploring Module Content with dir()

import math

print(dir(math))

Lists all available attributes and methods inside a module.

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9. Using help() for Module Documentation

import math

help(math)

Displays detailed documentation of a module and its components.

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10. Module Search Path (sys.path)

import sys

print(sys.path)

Shows directories Python searches to locate modules, including:

• Current directory

• Standard library path

• Site-packages

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