Python Enumerate
To start we’re going to create a simple dataframe in python:
If you want to watch a video on our YouTube channel based around the tutorial it’s embedded below.
Example 1 - Enumerate on List
For our first example let’s Enumerate on a list. We will look at a list of sports.
sports = ['ultra running', 'cricket', 'baseball'] for index, sport in enumerate(sports): print(index, sport) 0 ultra running
1 cricket
2 baseball
Example 2
We can modify Enumerate to start on 1 instead of 0.
for index, sport in enumerate(sports, start=1): print(index, sport) 1 ultra running
2 cricket
3 baseball
Example 3 - Enumerate String
While the first two examples look at a list, we can also Enumerate on a String since it’s an iterable.
Each letter will have an index.
word = "DiMaggio" for index, letter in enumerate(word): print(index, letter) 0 D
1 i
2 M
3 a
4 g
5 g
6 i
7 o
Example 4 - Tuples
Now let’s look at another common iterable which is tuples.
teams = ('Rays', 'Yankees', 'Red Sox') for index, team in enumerate(teams): print(index, team) 0 Rays
1 Yankees
2 Red Sox
Example 5 Convert Enumerate to List
You can also convert the final result into a list.
numbers = [17, 27, 99] enumerated_list = list(enumerate(numbers)) print(enumerated_list) [(0, 17), (1, 27), (2, 99)]
Example 6 - Dictionary
Another iterable we will take a look at is a dictionary.
my_dict = {'Ohtani': 17, 'Trout': 27, 'Judge': 99} for index, key in enumerate(my_dict): print(index, key, my_dict[key]) 0 Ohtani 17
1 Trout 27
2 Judge 99
Example 7 - Enumerate with list comprehension
By using list comprehension you can create a new list in one line of code. We can also use enumerate inside of it.
numbers = [17, 27, 99] indexed_numbers = [(index, number) for index, number in enumerate(numbers)] print(indexed_numbers) [(0, 17), (1, 27), (2, 99)]
Example 8 - Enumerate with Logic
Often when working with enumerate, you’ll deal with some sort of logic. Let’s take out hr_hitters list and only print out the hitters where there is an even index.
hr_hitters = ['Bonds', 'Aaron', 'Ruth', 'Pujols', 'Rodriguez'] for index, hitter in enumerate(hr_hitters): if index % 2 == 0: print(f"Even index {index}: {hitter}") Even index 0: Bonds
Even index 2:Ruth
Even index 4: Rodriguez
Example 9 - Enumerate with ZIP
Zip allows us to combine multiple iterables. Let’s look at an example which uses both enumerate and Zip.Â
names = ['Ohtani', 'Trout', 'Judge'] numbers = [17, 27, 99] for index, (names, numbers) in enumerate(zip(names, numbers)): print(f"{index}: {names} wears number: {numbers}") 0: Ohtani wears number: 17
1: Trout wears number: 27
2: Judge wears number: 99
Example 10
if you want to update values within a list, you can also use Enumerate. This helps a ton as without this you would be required to create a new lisit.
hrs = [15, 21, 33] for index, value in enumerate(hrs): hrs[index] = value * 2 print(hrs) [30, 42, 66]
