From: John Kiopela (john.kiopela_at_[hidden])
Date: 2007-12-02 07:26:32
I'll copy my code tomorrow, I'm not at my workstation right now. However,
I'm pretty sure that adapting the iterator is faster than copying the
values/keys into a collection in advance.
John
On 11/30/07, chun ping wang <cablepuff_at_[hidden]> wrote:
>
> hey i am curious on the actual code you written. Cause i want to know if
> doing that is faster than copying an item to a container and like iterate
> over that.
>
> template
> <
> class T, class U,
> template <typename ELEM, typename = std::allocator<ELEM> >
> class CONT
> >
> CONT<T> getKeys(const boost::unordered_map<T, U>& data)
> {
> CONT<T> retCont;
> typedef typename boost::unordered_map<T, U>::value_type value_type;
> BOOST_FOREACH(value_type val, data)
> {
> retCont.push_back(val.first);
> }
> return retCont;
> }
>
> Note i am using keys instead of value but concept is the same.
> On Nov 30, 2007 1:59 AM, John Kiopela <john.kiopela_at_[hidden]> wrote:
>
> > Thanks a lot both. Transform Iterator did the trick.
> >
> > Kind regards,
> >
> > John
> >
> >
> > On Nov 29, 2007 9:04 PM, Niels Aan de Brugh <niels_at_[hidden]> wrote:
> >
> > > On 2007-11-29, John Kiopela <john.kiopela_at_[hidden]> wrote:
> > > >
> > > > I have been browsing through the docs, but I couldn't find anything
> > > useful.
> > > > Does Boost have a std::map<K, V>::iterator adaptor which iterates
> > > over the
> > > > values of the map only.
> > >
> > >
> > > What about using a boost::transform_iterator<>? Docs at:
> > >
> > > http://boost.org/libs/iterator/doc/transform_iterator.html
> > >
> > > You'd have to supply it with a function object that returns the
> > > 'second'
> > > member variable of the pair, e.g.
> > >
> > > struct get_pair_value
> > > {
> > > template< typename K, typename V >
> > > V operator()( std::pair< K, V > const& pr )
> > > { return pr.second; }
> > > };
> > >
> > > Or you could use Boost.Lambda.
> > >
> > > N.
> > >
> > >
> > > _______________________________________________
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> > > Boost-users_at_[hidden]
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> > >
> > >
> >
> >
> >
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>
>
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