Thinking about this some more leads me to believe a general purpose imerge taking any number of arguments will look neater, eg
def imerge(*generators): values = [ g.next() for g in generators ] while True: x = min(values) yield x for i in range(len(values)): if values[i] == x: values[i] = generators[i].next()
This kinda looks like it dies after the first generator is exhausted, but I'm not certain. An alternate version that doesn't search for 'i':
py> def imerge(*iterables): ... iters = [iter(i) for i in iterables] ... values = [i.next() for i in iters] ... while iters: ... x, i = min((val, i) for i, val in enumerate(values)) ... yield x ... try: ... values[i] = iters[i].next() ... except StopIteration: ... del iters[i] ... del values[i] ... py> list(imerge([1, 4, 7], [2, 5, 8], [3, 6, 9])) [1, 2, 3, 4, 5, 6, 7, 8, 9] py> list(imerge([3, 6, 9], [1, 4, 7], [2, 5, 8])) [1, 2, 3, 4, 5, 6, 7, 8, 9] py> list(imerge([1, 4, 7], [3, 6, 9], [2, 5, 8])) [1, 2, 3, 4, 5, 6, 7, 8, 9]
This means that this can be further simplified thus,
def hamming(): def _hamming(): yield 1 for n in imerge( imap(lambda h: 2*h, hamming2), imap(lambda h: 3*h, hamming3), imap(lambda h: 5*h, hamming5) ): yield n hamming2, hamming3, hamming5, result = tee(_hamming(), 4) return result
Nice.
Steve -- http://mail.python.org/mailman/listinfo/python-list
