gistfile1.txt

import numpy as np
from scipy.sparse import dia_matrix
import timeit

def matches(a, b):
    mask = dia_matrix((np.ones((1, a.size)).repeat(4, axis=0), np.arange(4)),
                      shape=(a.size, b.size), dtype=np.int)
    matches = a[mask.T.dot(mask.dot(a == b) == 4).astype(np.bool)]

if __name__ == '__main__':
    for p in [3, 5, 7]:
        print('1e%d -' % p, timeit.timeit('matches(np.arange(1e%d), np.arange(1e%d))' % (p, p),
                                         setup="from __main__ import matches, np, dia_matrix", number=100))