gistfile1.txt

#!/usr/bin/env python
#-*- coding:utf-8 -*-

import re
import pprint

r = re.compile(r'^([\d.]+[KGM]?) +(\w+)')

homes = []
# How much is a K or an M or a G worth?
sizemap = {"K":"*1024", "M": "*1024"*2, "G": "*1024"*3, "T": "*1024"*4}

for line in file('/tmp/homes'):
    size, name = r.match( line ).groups()
    # Calculate a math expression:
    # 24.5M turns into 24 * 1024 * 1024
    sizexpr = size
    for key, value in sizemap.items():
        sizexpr = sizexpr.replace(key, value)
        
    # Convert that back into a number
    realsize = eval(sizexpr)
    homes.append((realsize, size, name))
    
# Sort the entries in reverse by the number we computed
homes.sort(key= lambda i: - i[0])

# Print them
for entry in homes:
    print "%s   %s" % (entry[1], entry[2])