#!/usr/bin/env python
""" sorts lines (or tab-sep records) by md5.  (e.g. for train/test splits).
optionally prepends with the md5 id too. 
brendan o'connor - anyall.org - gist.github.com/brendano """
 
import hashlib,sys,optparse
p = optparse.OptionParser()
p.add_option('-k',  type='int', default=False)
p.add_option('-p', action='store_true')
opts,args=p.parse_args()
 
lines = sys.stdin.readlines()
getter=lambda s: hashlib.md5(s[:-1]).hexdigest()
if opts.k:
  getter=lambda s: hashlib.md5(s[:-1].split("\t")[opts.k-1]).hexdigest()
 
lines.sort(key=lambda s: getter(s))
for line in lines:
  if opts.p:  line = getter(line) + "\t" + line
  print line,