find-anagrams.py

def find_anagrams(hay, needle):
    primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101]
    f = lambda c : primes[ord(c.lower()) - ord('a')]
    needle_primes = map(f, needle)
    needle_primehash = reduce(mul, needle_primes)
    current_primehash = 1
    l = len(needle)
    locations = []
    for i,c in enumerate(hay):
        if i >= l:
            current_primehash //= f(hay[i - l])
        current_primehash *= f(c)

        if needle_primehash == current_primehash:
            locations.append((i - l + 1, hay[i-l+1:i+1]))
    return locations