Merge Algorithm

merge.py

def merge(streams):
  # Keep track of the least value in each stream.
  head = [stream.next() for stream in streams]
  while len(head):
    # Yield the least value of all streams.
    next = min(head)
    yield next
    index = head.index(next)
    try:
      # Get next value from that stream.
      head[index] = streams[index].next()
    except StopIteration:
      # Remove that stream if it is empty.
      head.pop(index)
      streams.pop(index)

def main():
  stream1 = iter([10, 20, 30])
  stream2 = iter([11, 21, 31, 41, 51])
  stream3 = merge([stream1, stream2])
  for i in stream3:
    print i

if __name__ == '__main__':
  main()