Python Looping Constructs: For, While, Nested Loops

Study Notes

Looping through Data with Python

Python's built-in features empower developers to work efficiently with data via various looping constructs. In this guide, we'll explore these loops and how they help us process information more effectively within our scripts.

There are three main types of loops used in Python:

For Loop
While Loop
Nested Loops

Let's break down each type, starting from the simplest one.

For Loop

The for loop iterates over elements contained in sequences like lists, tuples, strings, sets, dictionaries, etc., repeating some block of code once per element. This is very useful when you want to perform tasks repeatedly based on a collection of items.

numbers = [1, 2, 3, 4, 5]
for number in numbers:
    print(number)

Output:

You can also chain multiple statements inside a single line using parentheses.

my_list = ["apple", "banana", "orange"]
for item in my_list:
    print("Current Item:", item)
    if item == 'orange':
        print('Oranges are yummy!')

Output:

Current Item: apple
Current Item: banana
Oranges are yummy!
Current Item: orange

While Loop

In contrast to for, the while loop continues running its corresponding block until it reaches a specific condition. It allows infinite repetition of actions as long as the specified condition remains true.

i = 0
while i < 5:
    print(i)
    i += 1

Output:

Nested Loops

Nested loops occur when one loop is defined inside another. They allow us to manipulate multi-dimensional data structures such as matrices, tables, trees, etc..

Here's an example where two nested loops generate all possible combinations of letter pairs:

letters = ['A', 'B', 'C']
result = []
for first_letter in letters:
    for second_letter in letters:
        pair = f"{first_letter}{second_letter}"
        result.append(pair)
print(result)

Output:

['AA', 'AB', 'AC', 'BA', 'BB', 'BC', 'CA', 'CB', 'CC']

Throughout your journey learning Python, familiarity with loops will unlock diverse possibilities to handle and analyze large amounts of data gracefully, saving both time and effort.

Description

Discover Python's versatile looping constructs - for loop, while loop, and nested loops. Learn how to efficiently iterate over sequences and manipulate multi-dimensional data structures using nested loops. Mastering loops in Python opens up a world of possibilities for processing data effectively.