On Wed, Jan 11, 2017 at 8:51 AM, Peng Yu <pengyu...@gmail.com> wrote: > Hi, peekable from more-itertools only allow peeking an iterator. But > sometimes, one may want to take a look at an element, manipulate it, > then put it back to the iterator. Is there a class in python that can > help do this?
Not that I'm aware of, but maybe this recipe will help. from collections import deque class PushIterator: def __init__(self, iterable, push=()): self._iter = iter(iterable) self._pushed = deque(push) self._stopped = False def push(self, item): if self._stopped: raise RuntimeError('Cannot push onto exhausted iterator') self._pushed.append(item) def __iter__(self): return self def __next__(self): if self._pushed: return self._pushed.pop() try: return next(self._iter) except StopIteration: self._stopped = True raise -- https://mail.python.org/mailman/listinfo/python-list