Multi Level sorting example in Python

multilevelsort.py

#!/usr/bin/env python

## An alternative approach for sorting list of dicts by multiple
## levels of criteria
## Original example: http://sleepythread.blogspot.in/2012/08/sorting-hash-on-more-than-one-key-with.html

import pprint

pp = pprint.PrettyPrinter(indent=4)

def compare_two(p, q, direction='asc'):
    if direction == 'desc':
        p, q = q, p
    if p < q:
        return -1
    elif p > q:
        return 1
    else:
        return 0


def comparator(a, b):
    cmp_age = compare_two(a['age'], b['age'])
    if cmp_age != 0:
        return cmp_age
    cmp_height=compare_two(a['height'], b['height'], 'desc')
    if cmp_height != 0:
        return cmp_height
    return compare_two(a['weight'], b['weight'])


students = [{'sno': 1, 'age': 10, 'weight': 130, 'height': 170}, 
            {'sno': 2, 'age': 8, 'weight': 130, 'height': 170}, 
            {'sno': 3, 'age': 8, 'weight': 110, 'height': 180}, 
            {'sno': 4, 'age': 8, 'weight': 110, 'height': 170}, 
            {'sno': 5, 'age': 7, 'weight': 130, 'height': 170}]


pp.pprint(sorted(students, cmp=comparator))