10 Helpful Features to Use in a for Loop in Python

Simplify your iterations with just the built-in features

Photo by Roman Synkevych on Unsplash

Just like other programming languages, we use for loops to perform repetitive work in Python. The most general form of a for loop takes the following format in Python:

for item in iterable:
    # the operation goes here

We often use lists to store data in our project. We can use the list object in a for loop, as shown below.

fruits = ["pineapple", "banana", "grape"]
for fruit in fruits:
    print(fruit)

Beyond the most common form, there are a variety of techniques that we can apply to a for loop, which allows us to write better iteration.

Without further ado, let’s get it started.

1. Enumerate Items with enumerate

In a for loop, sometimes you need to know the index of the item or the counter of the item in the iterable. For contrast, the following shows you a possible solution.

for item_i in range(len(fruits)):
    fruit = fruits[item_i]
    print(f"#{item_i+1}: {fruit}")
#1: pineapple
#2: banana
#3: grape

However, a better way to implement this functionality is to use the built-in enumerate function, which directly creates a counter together with the item of the iterable.

for item_i, fruit in enumerate(fruits, start=1):
    print(f"#{item_i}: {fruit}")
#1: pineapple
#2: banana
#3: grape

Note that I set the start parameter to be 1 because I wanted the counter to start with 1. If you want, you can set a different starting value.

2. Reverse Items with reversed

Sometimes, you need to reverse the iterable for iteration. With a list object, you may use the reverse function, which reverses the items of the list.

fruits.reverse()
for fruit in fruits:
    print(fruit)
grape
banana
pineapple

The same functionality can be easily accomplished with the reversed function, as shown below. Please note that because we’ve reversed the list, when I use reversed again…