Iterate Through a List Using For Loop in Python

In Python, you can iterate through a list using a for loop to access each element one by one. Through iteration, we can perform operations like printing, modifying, or applying logic to each item in the list.

Examples

1. Iterating Through a List of Numbers

We can use a for loop to iterate over a list of numbers and print each element.

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# List of numbers
numbers = [1, 2, 3, 4, 5]

# Iterating through the list using a for loop
for num in numbers:
    print(num)

Here, we have a list named numbers containing integers. The for loop iterates over the list, assigning each element to the variable num, which is then printed in each iteration.

Output:

1
2
3
4
5

2. Iterating Through a List of Strings

Lists can store strings, and we can iterate through them using a for loop.

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# List of fruits
fruits = ["apple", "banana", "cherry"]

# Iterating through the list
for fruit in fruits:
    print("I like", fruit)

We have a list called fruits containing three string elements. The for loop assigns each element to the variable fruit and prints a message for each fruit.

Output:

I like apple
I like banana
I like cherry

3. Iterating Through a List Using enumerate()

The enumerate() function allows us to iterate over a list while keeping track of the index.

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# List of colors
colors = ["red", "green", "blue"]

# Iterating using enumerate() to get index and value
for index, color in enumerate(colors):
    print(f"Color at index {index} is {color}")

We use enumerate() to get both the index and value while iterating through the list colors. The index is assigned to index and the value to color, which are printed in each iteration.

Output:

Color at index 0 is red
Color at index 1 is green
Color at index 2 is blue

4. Iterating Through a List Using range() and len()

We can use range() with len() to iterate through a list by index.

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# List of countries
countries = ["USA", "Canada", "Germany"]

# Iterating using range() and len()
for i in range(len(countries)):
    print(f"Country at index {i}: {countries[i]}")

Here, we use range(len(countries)) to generate index values. The loop variable i represents the index, which we use to access elements from countries.

Output:

Country at index 0: USA
Country at index 1: Canada
Country at index 2: Germany

5. Iterating Through a List of Tuples (Unpacking)

If the list contains tuples, we can iterate and unpack values inside the loop.

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# List of tuples containing student names and grades
students = [("Alice", 85), ("Bob", 90), ("Charlie", 78)]

# Iterating through list of tuples
for name, grade in students:
    print(f"{name} scored {grade} marks")

The list students contains tuples with names and grades. In each iteration, the for loop unpacks each tuple into variables name and grade to display their values.

Output:

Alice scored 85 marks
Bob scored 90 marks
Charlie scored 78 marks

Conclusion

There are multiple ways to iterate through a list using a for loop:

  1. Basic iteration: Access each element directly.
  2. Iterating through strings: Useful for lists containing words or characters.
  3. Using enumerate(): Retrieves both index and value.
  4. Using range() and len(): Iterates by index.
  5. Unpacking tuples: Extracts multiple values inside the loop.