PyCon Anagrams

anagrams.py

#!/usr/bin/env python

"""Checks for anagrams in stdin.

Example: $ curl -sL http://thumb.tk/8Qdr | python anagrams.py
"""

import itertools
import sys


def flatten(words):
    """Flattens, lowers, and sorts characters in an iterable."""

    return ''.join(sorted(itertools.chain(*map(lambda x: x.lower(), words))))


def strip(characters):
    ("Strips invalid characters from an iterable, leaving only alpha "
     "and whitespace.")

    def valid(s):
        return s.isalpha() or s.isspace()

    return ''.join(filter(valid, characters))


results = []

sentence = sys.stdin.readline()
words = strip(sentence).split()
pairs = itertools.combinations(words, 2)
inner, outer = itertools.tee(pairs)

# Without coverting outer to a list, it would be empty after the first
# iteration.
outer = list(outer)

for x in inner:
    x_original = x
    x = flatten(x)

    for y in outer:
        y_original = y

        if sorted(x_original) == sorted(y_original):
            continue

        y = flatten(y)

        if x != y:
            continue

        if (x_original, y_original) in results:
            continue

        if (y_original, x_original) in results:
            continue

        results.append((x_original, y_original))

for match in results:
    output = (x for t in match for x in t)
    print '"{}, {}" is an anagram for "{}, {}"'.format(*output)