[Tutor] newbie code review please!

[tyler]

On Sun, Feb 03, 2008 at 04:35:08PM -0500, Kent Johnson made several
helpful suggestions:

Thanks!

That cleaned up a lot. However, I couldn't figure out a way to do
random.choice(word_hash[(w1, w2)]) on a dict with set-type values. The
closest I could get was word_hash[(w1, w2)].pop(), but then I need to
add a few lines to put the value back into the set afterwards. Is
there a way to randomly lookup a value in a set without removing it
from the set? I had better success with collections.defaultdict(list),
as pasted below.

Cheers,

Tyler

#! /usr/bin/python2.5

import sys, random, collections

word_max = 1000

# Read in file
infile = open(sys.argv[1], 'r')
ifstring = infile.read()

# break file into words
iflist = ifstring.split()

# build hash of form (prefix1, prefix2): [word]
word_hash = collections.defaultdict(list)
for i in range(len(iflist) - 2):
    tk = tuple(iflist[i:i+2])
    tv = iflist[i+2]
    if tv not in word_hash[tk]:
        word_hash[tk].append(tv)

word_hash[(iflist[-2], iflist[-1])].append('\n')

# output first two words
w1, w2 = iflist[0:2]
print w1, w2,

# generate new words from hash
for word_num in range(word_max):
    w1, w2 = w2, random.choice(word_hash[(w1, w2)])
    print w2,
    if w2 == '\n':
        break