Taking details from a map and saving it into another?

I have a map like this

map<string, pair< pair<int, int>, string> >

what is the easiest way to get only the two strings and save into another map like this

map<string, string>

? I mean is there another way other than something like this??

    map<string, pair< pair<int, int>, string> >  info;
    map<string, pair< pair<int, int>, string> >::iterator开发者_StackOverflow i;
    map<string, string> something;


    for(i=info.begin(); i!=info.end(); ++i)
        something[*i).first] = ((*i).second).second;

First, I'd define a proper type:

struct Mapped
{
    int someSignificantName;
    int anotherName;
    std::string yetAnother;
};

There are almost no cases where std::pair is an acceptable solution (except for quick hacks and tests). Given that, you define a mapping functional object:

struct Remap
    : std::unary_operator<std::pair<std::string, Mapped>,
                          std::pair<std::string, std::string> >
{
    std::pair<std::string, std::string> operator()(
            std::pair<std::string, Mapped> const& in ) const
    {
        return std::make_pair( in.first, in.second.yetAnother );
    }
};

, then use std::transform:

std::transform( in.begin(), in.end(),
                std::inserter( out, out.end() ),
                Remap() );

map<string, pair< pair<int, int>, string> > map1 /* = ... */;
map<string, string> map2;

BOOST_FOREACH (const pair<string, pair< pair<int, int>, string> > >& it, map1) {
   map2[it.first] = it.second.second;
}

By the way, EWTYPE.

The easiest way is to write simple for-loop that just works.

typedef pair<pair<int, int>, string> strange_pair_t;
typedef map<string, strange_pair_t> strange_type_t;
strange_type_t src_map;

map<string, string> dst_map;
for(strange_type_t::const_iterator it = src_map.begin(); it!=src_map.end(); ++it)
{
  dst_map.insert( make_pair( it->first, it->second.second ) );
}

The tricky way ("one-liner"):

std::transform( src_map.begin(), src_map.end(), inserter(dst_map, dst_map.end()), 
    boost::lambda::bind( 
        boost::lambda::constructor<pair<string,string>>(), 
        boost::lambda::bind( &strange_type_t::value_type::first, boost::lambda::_1 ), 
        boost::lambda::bind( &strange_pair_t::second, boost::lambda::bind( &strange_type_t::value_type::second, boost::lambda::_1 ) )
    )
);

C++0x way:

for_each( src_map.begin(), src_map.end(), [&dst_map](const strange_type_t::value_type& value) {
    dst_map.insert( make_pair( value.first, value.second.second ) ); } );