Efficient Fibonacci Sequence generator in Python.

fibgen.py

# -*- coding: utf-8 -*-

'''

  Code Samples: Fibonacci Sequence
  Author: Sam Gammon <[email protected]>
  Description:
    Recursively generates items in the Fibonacci Sequence, up to kw/positional arg `limit`.
    Supports starting anywhere in the sequence, assuming `previous` and `current` are truly
    part of the Fibonacci set.

'''

def fib(limit=10000, previous=1, current=0):

  ''' Generate items in the fibonacci sequence,
      from the pair (`previous`, `current`) to `limit`.
      All parameters are ``int``s, and one need only
      pass a 'limit,' which is also optional and defaults
      to ``10,000``.
      
      :param limit: Value limit to generate numbers to.
      :param previous: Former value in the moving window.
      :param current: Latter value in the moving window.

      :returns: ``int`` values that are successively greater
      members of the Fibonacci sequence. '''

  if limit and (current >= limit): raise StopIteration()

  yield previous + current
  for next in fib(limit, current, (previous + current)):
    yield next


if __name__ == '__main__':
  for i in fib(): print i