multirember&co

[attn.steven.kuo at gmail.com]

On Apr 19, 9:13 am, Anton Vredegoor <anton.vredeg... at gmail.com> wrote:


(snipped)

>
> > How about this one?
>
> No that can result in an infinite loop after yet another
>
> print it1.next()
>
> This one however ...
>
> from collections import deque
>
> class sentinel(object):
>      pass
>
> class myiter(object):
>
>      def __init__(self,seq):
>          self.seq = seq
>          self.index = -1
>
>      def __iter__(self):
>          return self
>
>      def next(self):
>          self.index +=1
>          if self.index < len(self.seq):
>              return self.seq[self.index]
>          else:
>              return sentinel
>
> def xsplitter(seq, pred):
>      Q = deque(),deque()
>      it = myiter(seq)
>      def gen(p):
>          for x in it:
>              while Q[p]:  yield Q[p].popleft()
>              if x is sentinel:  break
>              if pred(x) == p:  yield x
>              else:
>                  Q[~p].append(x)
>                  for x in gen(p):  yield x
>      return gen(1),gen(0)
>
> def test():
>      L = 'a', 1, 2, 'a'
>      it1, it2 = xsplitter(L, lambda x: x == 'a')
>      print it1.next()
>      print it2.next()
>      print it1.next()
>      print it2.next()
>
> if __name__=='__main__':
>      test()
>
> A.


Um, no.  That one stops prematurely if
your input sequence is:

L = 1, 2, 3, 'a', 'a'


You get points for persistence, however.  :)

--
Regards,
Steven