reduce() function in Python is part of the
functools module and is used to perform a specified function on a sequence of elements, reducing it to a single value. It takes two parameters: the function to be applied and the iterable sequence to be reduced.
function: The function to be applied. It should take two arguments and return a single value. The function is applied cumulatively to the items of the iterable from left to right.
iterable: The sequence of elements to be reduced.
In general, the
reduce() function is mostly used when working with lists.
Some examples of using the
reduce() function in practice, in order from basic to advanced.
Summing a list of numbers
reduce() function can help us easily calculate the sum of all numbers in a list:
from functools import reduce numbers = [2023, 2024, 2025, 2026, 2027] sum = reduce(lambda x, y: x + y, numbers) print(sum) # 10125
Flattening a list of lists
You can use the
reduce() function to flatten a list of lists into a single list with only a single line of code:
from functools import reduce nested_list = [[1, 2], [3, 4], [5, 6]] flat_list = reduce(lambda x, y: x + y, nested_list) print(flat_list) # Output: [1, 2, 3, 4, 5, 6]
Finding the longest string
Let’s say we have a list of strings. What we need to do is to find the longest string from there. The
reduce() function can help us get the job done without spending too much effort:
from functools import reduce strings = ["dog", "slingacademy.com","turtle", "dark hole", "banana"] longest = reduce(lambda x, y: x if len(x) > len(y) else y, strings) print(longest) # slingacademy.com
Finding the minimum and maximum values
Here’s the code:
from functools import reduce numbers = [12, 45, 23, 67, 9] minimum = reduce(lambda x, y: x if x < y else y, numbers) print(minimum) # Output: 9 maximum = reduce(lambda x, y: x if x > y else y, numbers) print(maximum) # Output: 67
That’s it. The tutorial ends here. Happy coding & have a nice day!