Access the index of a for loop

David Y.

—March 15, 2023

The ProblemThe Problem

How do I access the index when iterating over a sequence inside a for loop?

The SolutionThe Solution

We can use Python’s built-in enumerate() function to do this. For each item in an iterable sequence such as a list, this function will return a tuple containing the item’s index and the item itself. Therefore, our code will look like this:

products = ["Apples", "Oranges", "Bananas"]

for idx, product in enumerate(products):
    print(f"{idx}: {product}")

This code will produce the following output:

0: Apples
1: Oranges
2: Bananas

If we would prefer to start the index from 1 (or any other number), we can specify this using enumerate()’s start parameter, as below:

products = ["Apples", "Oranges", "Bananas"]

for idx, product in enumerate(products, start=1):
    print(f"{idx}: {product}")

This will produce the following output:

1: Apples
2: Oranges
3: Bananas

The index can also be accessed without using the enumerate() function by iterating over the length of the iterable sequence as below:

products = ["Apples", "Oranges", "Bananas"]

for idx in range(len(products)):
    print(f"{idx}: {products[idx]}")

This code will produce the following output:

0: Apples
1: Oranges
2: Bananas