Key in Min/Max function in Python

February 5, 2019 One-minute read

TIL

So I was browsing TensorFlow doc on the Dataset API, when I stumbled across something which eventually led me to learn this:

You can pass a key function(or a lambda) to the min/max function in Python.

Here is a sweet example:

def sumDigit(num):
    sum = 0
    while(num):
        sum += num % 10
        num = int(num / 10)
    return sum

# using min(arg1, arg2, *args, key)
print('Minimum is:', min(100, 321, 267, 59, 40, key=sumDigit))

# using min(iterable, key)
num = [15, 300, 2700, 821, 52, 10, 6]
print('Minimum is:', min(num, key=sumDigit))

Source : https://www.programiz.com/python-programming/methods/built-in/min