Sorting a list with two criteria in python

Matthieu Choplin

We want to sort a list of elements with the first element in ascending order and the second element in descending order.

Using the lambda function:

occurences = {'bat': 2, 'mat': 1, 'cat': 3}
sorted(occurences.items(), key=lambda x: (-x[1], x[0]))

The -x[1] is for the reversed sort.

By order of priority, we first sort with the 2nd element (x[1]), then with the 1st element (x[0])

Example for an interview question: