Loop Through List Items

Looping through list items in Python refers to iterating over each element within a list. We do so to perform the desired operations on each item. These operations include list modification, conditional operations, string manipulation, data analysis, etc.

Python provides various methods for looping through list items, with the most common being the for loop. We can also use the while loop to iterate through list items, although it requires additional handling of the loop control variable explicitly.

Loop Through List Items with For Loop

A for loop in Python is used to iterate over a sequence (like a list, tuple, dictionary, string, or range) or any other iterable object. It allows you to execute a block of code repeatedly for each item in the sequence.

Example

lst = [25, 12, 10, -21, 10, 100]
for num in lst:
   print(num, end=' ')

Output:

25 12 10 -21 10 100

Loop Through List Items with While Loop

A while loop in Python is used to repeatedly execute a block of code as long as a specified condition evaluates to True.

Example

my_list = [1, 2, 3, 4, 5]
index = 0
while index < len(my_list):
   print(my_list[index])
   index += 1

Output:

1
 2
 3
 4
 5

Loop Through List Items with Index

We can loop through list items using an index by iterating over a range of indices corresponding to the length of the list and accessing each element using the index within the loop.

Example

lst = [25, 12, 10, -21, 10, 100]
for i in range(len(lst)):
   print(f"lst[{i}]:", lst[i])

Output:

lst[0]: 25
lst[1]: 12
lst[2]: 10
lst[3]: -21
lst[4]: 10
lst[5]: 100

Iterate using List Comprehension

A list comprehension in Python is a concise way to create lists by applying an expression to each element of an iterable.

Example

numbers = [1, 2, 3, 4, 5]
squared_numbers = [num ** 2 for num in numbers]
print(squared_numbers)

Output:

[1, 4, 9, 16, 25]

Iterate using the enumerate() Function

The enumerate() function in Python is used to iterate over an iterable object while also providing the index of each element.

Example

fruits = ["apple", "banana", "cherry"]
for index, fruit in enumerate(fruits):
   print(index, fruit)

Output:

0 apple
1 banana
2 cherry