Python example: Anagram counter

anagram-counter.py

from collections import defaultdict

def anagram_counter(words, n):
    lookup = defaultdict(set)
    for word in words:
        if len(word) == n:
            lookup[lookup_key(word)].add(word)

    num_anagrams = 0
    for anagram_words in lookup.values():
        # An anagram must have at least two words with the same letters
        if len(anagram_words) > 1:
            num_anagrams += 1

    return num_anagrams

def lookup_key(word):
    # Return the sorted, lower-case letters of the word
    return "".join(sorted(word.lower()))