reverse second sort characteristic in python sorted()

Question

I\'m trying to sort a list and I can\'t figure out to reverse the order of a second sorting characteristic.

import math
ps = {1:(1,1),2:(3,2),3:(3,-3),4:(-3,4),         


        

Answer 1

You can do two sorts, least significant first. Python sorting is stable, so the order determined by the first sort will hold when you do the second.

for c in sorted(sorted(l, key = lambda t:math.sqrt((0-t[1][0])**2 + (0-t[1][1])**2)), key = lambda t:t[0], reverse=True):

This method works even when the keys aren't numeric.