Demo/comparisons/sortingtest.py

#! /usr/bin/env python

# 2)  Sorting Test
# 
#     Sort an input file that consists of lines like this
# 
#         var1=23 other=14 ditto=23 fred=2
# 
#     such that each output line is sorted WRT to the number.  Order
#     of output lines does not change.  Resolve collisions using the
#     variable name.   e.g.
# 
#         fred=2 other=14 ditto=23 var1=23 
# 
#     Lines may be up to several kilobytes in length and contain
#     zillions of variables.

# This implementation:
# - Reads stdin, writes stdout
# - Uses any amount of whitespace to separate fields
# - Allows signed numbers
# - Treats illegally formatted fields as field=0
# - Outputs the sorted fields with exactly one space between them
# - Handles blank input lines correctly

import regex
import string
import sys

def main():
	prog = regex.compile('^\(.*\)=\([-+]?[0-9]+\)')
	def makekey(item, prog=prog):
		if prog.match(item) >= 0:
			var, num = prog.group(1, 2)
			return string.atoi(num), var
		else:
			# Bad input -- pretend it's a var with value 0
			return 0, item
	while 1:
		line = sys.stdin.readline()
		if not line:
			break
		items = string.split(line)
		items = map(makekey, items)
		items.sort()
		for num, var in items:
			print "%s=%s" % (var, num),
		print

main()