python-custom-sort-function

This tiny post is for me, as I was had two chanlleges I did that required "custom sort function". It was super hard to "google" it as things were different in python 2 and I'm using python 3 now.

The bottom line it does the same but just weird sytax.

# python 3
from typing import List
from functools import cmp_to_key


weirdList = [
    {
        "a": 1,
        "b": 3,
    },
    {
        "a": 1,
        "b": 2,
    },
    {
        "a": 2,
        "b": 1,
    },
]
def owncomp(a, b):
    if a["a"] > b["a"]:
        return 1
    elif a["a"] < b["a"]:
        return -1
    
    if a["b"] > b["b"]:
        return 1
    else:
        return -1

rs = sorted(weirdList, key=cmp_to_key(owncomp))
print(rs)

Simpler Sort Option (only changing key)

intervals.sort(key=lambda x: x["a"])

class LargerNumKey(str):
    def __lt__(x, y):
        print(x, y, x+y > y+x)
        return x+y > y+x

largest_num = sorted(map(str, nums), key=LargerNumKey)