Python – sorting function in python


I'm trying to sort a list of objects according to my criteria.

Here is my sorting function:

def sort_pots(self, pot1, pot2):
    coeff1 = ((pot1.movable + pot1.convertible) /
    coeff2 = ((pot2.movable + pot2.convertible) /

    if coeff1 > coeff2:
        return 1
    elif coeff1 == coeff2:
        return -
        return -1

What i would like to achieve is:
if coeff1 > coeff2, pot1 is before pot2
if coeff1 == coeff2, the one with the highest total is before
else (coeff2 > coeff1), pot2 is before pot2

and the function doesn't seem to work accordingly. I've got a bunch ordered according to total but not with same coeff.
I've (convertible, movable, total): 0, 0, 1 and later 0, 3, 4 and then 31, 228, 1584 and then 1, 0, 1

Here is the beginning of the definition of the class of pot1 and pot2:

class Potential:
    def __init__(self,conf_opt):
        self.conf_opt = conf_opt = 0
        self.movable = 0
        self.convertible = 0


Best Solution

Does the following work?

def coef(pot):
    return (pot.movable + pot.convertible) / float(

l.sort(key=lambda x: (coef(x),, reverse=True)

It should even be faster (key is better than cmp).