Looping Trough Lists and Tuples

For-loops are extremely useful when working with lists and tuples, as they allow you to iterate over each element and perform operations on them. Unlike range-based loops, iterating directly over lists or tuples simplifies code and avoids common errors, such as index out of bounds.

Looping Through a List

Here’s a basic example of looping through a list:

letters = ["A", "B", "C", "D"]
for element in letters:
    print(element)
# Output:
# A
# B
# C
# D

In this example, the loop iterates over each element in the list letters, printing each letter one by one.

You can modify elements of a list directly within a loop. Here’s how to add an “x” to each entry in the list letters:

for i in range(len(letters)):
    letters[i] = letters[i] + "x"
print(letters)
# Output:
# ['Ax', 'Bx', 'Cx', 'Dx']

If you need to create a new list based on the elements of an existing list, you can initialize an empty list and append to it within the loop:

a = ["A", "B", "C", "A", "B", "A", "A"]
test = []  # this is an empty list
for i in range(len(a)):
    test.append(a[i].lower())

print(test)
# Output:
# ['a', 'b', 'c', 'a', 'b', 'a', 'a']

Looping Through a Tuple

Tuples are similar to lists but are immutable, meaning their elements cannot be changed after creation. You can loop through tuples just like lists:

colors = ("red", "green", "blue")
for color in colors:
    print(color)
# Output:
# red
# green
# blue