What is an iteration in Python?

Angus 54 Published: 08/04/2024

What is an iteration in Python?

I'd be happy to explain what an iteration is in Python!

In Python, iteration refers to the process of repeatedly executing a block of code for each item in a collection, such as a list, tuple, dictionary, or set. This is typically achieved using loops, which are essential in programming.

Python provides several ways to iterate over collections, including:

For Loop: A for loop allows you to execute a block of code for each item in a collection. The general syntax is for variable in iterable: where variable takes on the value of each item in the iterable. 
    fruits = ['apple', 'banana', 'cherry']

for fruit in fruits:


print(fruit)
While Loop: A while loop allows you to execute a block of code as long as a certain condition is met. In iteration, you can use a while loop with an index variable to traverse through a collection. 
    numbers = [1, 2, 3, 4, 5]

i = 0


while i < len(numbers):


print(numbers[i])


i += 1
List Comprehensions: List comprehensions are a concise way to create new lists from existing ones. They can also be used for iteration. 
    numbers = [1, 2, 3, 4, 5]

squared_numbers = [n**2 for n in numbers]


print(squared_numbers)  # prints [1, 4, 9, 16, 25]
Generators: Generators are a type of iterable that can be used to iterate over a collection without storing the entire collection in memory. 
    def infinite_sequence():

num = 0


while True:


yield num


num += 1


seq = infinite_sequence()


for _ in range(10):


print(next(seq))

In Python, iteration is often used to:

Process collections of data (e.g., lists, dictionaries) Perform tasks on each item in a collection Traverse through complex data structures (e.g., trees, graphs)

Iteration is an essential concept in programming and is widely applicable. By mastering different types of iterations in Python, you can write more efficient and effective code.

In conclusion, iteration in Python refers to the process of repeatedly executing a block of code for each item in a collection. It's an important concept that allows you to work with collections of data and perform tasks on each item.

What is iteration in Python w3schools?

I'm happy to help!

Iteration in Python refers to the process of repeatedly executing a block of code as long as a certain condition is met. In other words, it's the ability to execute a piece of code multiple times with slight changes or modifications each time.

In Python, iteration can be achieved through various methods, including:

For Loops: A for loop is used to iterate over a sequence (such as a list, tuple, or string) and execute a block of code for each item in the sequence. 
fruits = ['apple', 'banana', 'cherry']

for fruit in fruits:


print(fruit)

In this example, the loop iterates over the fruits list and prints each fruit.

While Loops: A while loop is used to iterate as long as a certain condition remains true. 
i = 0

while i < 5:


print(i)


i += 1

In this example, the loop iterates from i=0 to i<5, printing each value of i.

List Comprehensions: A list comprehension is a concise way to create a new list by iterating over an existing list and applying a transformation. 
numbers = [1, 2, 3, 4, 5]

squared_numbers = [x**2 for x in numbers]


print(squared_numbers)  # [1, 4, 9, 16, 25]

In this example, the list comprehension creates a new list squared_numbers by iterating over the original list numbers, squaring each value, and collecting the results.

Generator Expressions: A generator expression is similar to a list comprehension but returns an iterator instead of a list. 
numbers = [1, 2, 3, 4, 5]

squared_numbers = (x**2 for x in numbers)


for num in squared_numbers:


print(num)  # prints the same output as above

In this example, the generator expression creates an iterator squared_numbers that yields each square number when iterated over.

Iteration is a fundamental concept in programming and is essential for tasks such as:

Processing large datasets Performing calculations or transformations on data Implementing algorithms and logic

By mastering iteration in Python, you'll be able to write efficient and effective code that can handle complex tasks with ease!

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