Hello Adán,
Adán Cosgaya
hi,i am new using the multiindex library, and I need to do the following.I have a set of d-dimensional points (e.g (3,5,8,9,5) is a 5-dimensional point), and I need to sort the points on each of the coordinates. I want to store the points in a vector,
Do you mean that the points *are* vectors or that, moreover, they are stored in a vector (thus, a vector of vectors)? If the latter, why do you want to have them in a vector? Does not having them stored in the multi_index_container suffice? In the following I assume that the points are stored only in a multi_index_container whose first index is of type sequenced (std::list-like), which gives you the free-positioning interface you seem to need. If this is not what you're after please tell me so.
and use multiindex to have all the points (vectors in this case) sorted in each of the coordinates [...] would you mind pointing me in the right direction with an example of how to do it with multiindex library? thanks
You only need to define an appropriate key extractor
for the N-th element of a vector:
template<int N>
struct nth_coordinate
{
typedef int result_type;
int operator()(const std::vector<int>& x)const
{
return x[N]; // or .at(N) for greater safety
}
};
so that the multi_index_container definition becomes:
typedef multi_index_container<
std::vector<int>,
indexed_by<
sequenced<>,
ordered_non_unique
multi_index_t;
Does this help? If for some reason the sequenced index at position #0 does not suffice, in Boost 1.34 there will be random access indices which are more similar to a vector, see http://tinyurl.com/psr6o . Good luck with your project, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo