Python-按第二个元素然后按第三个元素对嵌套列表进行排序

Question

So i am sorting a list of nested lists of integers by firstly the 2nd element (in ascending order), which I have done using the following code:

my_list.sort(key=lambda x: x[2])  

Now, if there are repeats in the second element, I would like to then sort the list by the 3rd element (in descending order). How would I go about this?

Answer 1

You can use a key function that returns a tuple instead. Negate the numeric value of an item if you want it to be sorted in the opposite direction.

my_list.sort(key=lambda x: (x[2], -x[3]))

Note that the index of 2 actually refers to the third item, and the index of 3 refers to the fourth item, but I assume that the index of 2 in the code you posted is the item you want to sort first.