[mlpack] How to keep object when searching neighbors?

[Ryan Curtin]

On Thu, Jan 16, 2014 at 11:28:53AM +0800, Li Dong wrote:
> > Ok, in that case my idea will work; build a tree on MeshCell points,
> > then use single-tree NeighborSearch during each iteration.  It'll look
> > something like this...
> > 
> > {{{
> >  using namespace mlpack;
> > 
> >  arma::mat meshPoints; // Constructed somehow
> >  arma::mat tracerPoints; // Constructed somehow
> > 
> >  AllkNN allknn(meshPoints, tracerPoints, false /* not naive */, true /* single mode */);
> > 
> >  while (stillRunning)
> >  {
> >    // recalculate tracer points
> >    ...
> > 
> >    arma::mat distances;
> >    arma::Mat<size_t> neighbors;
> >    allknn.Search(k, neighbors, distances);
> >  }
> > }}}
> 
> Where do I build the tree for MeshCell points? Or MLPACK builds it for me when in single mode?

The AllkNN object (which is a typedef for NeighborSearch) will build and
internally hold the tree for the reference points, and because
singleMode == true, it won't build the tree for the query points.  It is
possible to make your own tree and pass that in, too, if that is what
you prefer.

-- 
Ryan Curtin    | "So, it's just you 57 punks against KUNG FU JOE?"
ryan at ratml.org |   - Kung Fu Joe