Question

Is there any standard implementation (meaning stdlib or boost) of an iterator that wraps another iterator and gives only each nth element of it?

I first thought this would be possible with a fitting predicate and boost::filter_iterator, but the predicate gets only the value and not the base iterator, so it cannot tell the distance to the start.

Edit
To give some more information:
The iterator should be compatible with functions like std::transform or std::copy.
So it should be used like stdlib iterators.

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Answer 1

Boost.Range provides a stride adaptor. Using boost::begin/boost::end would net you the associated iterators.