switch recipe?

[Terry Reedy]

"Mark McEahern" <marklists at mceahern.com> wrote in message > Perhaps
what I'm still looking for is a way to
> weave-two-iterators-with-a-function all at once.  One solution would
be to
> modify or wrap repeating_alternator() so that it was finite--then I
could
> just use map.

*IF* you know the 'length' of iterator, or the iterable it is based
on, as in the examples used in preious articles in this thread, this
is easy and clean:

def firstn(it, n):
  while n:
    yield it.next()
    n -= 1

n = len(iterator) # or whatever
map(color_item, iterator, firstn(alternator, n))

Terry J. Reedy