Children of given Node of the Tree

[boblukas]

Hi everyone,

for an application I need to know the hierarchy of my rtree. In particular, given a Node, I'd like to know its children.

I've seen that in this SO question there's al ink to the following line:

geometry/include/boost/geometry/index/detail/rtree/utilities/print.hpp

Line 160 in f92671b

elements_type const& elements = rtree::elements(n);

where n is an InternalNode. From my understanding, it->first is the bounding box, while it->second is the indexable. However, I don't see how one can query the children of a specific node. Is there any way to find them?

Any help is highly appreciated, as I am completely stuck so far.

Best,
Lukas

[awulkiew]

The elements of internal nodes are pairs of bounding box and pointer to child node. So it->second is a pointer which can be used for depth-first tree traversal like this:

geometry/include/boost/geometry/index/detail/rtree/utilities/print.hpp

Line 178 in f92671b

rtree::apply_visitor(*this, *it->second);

Indexables (points, boxes or segments) can be extracted from elements of leaf nodes (aka values of the rtree) like this:

geometry/include/boost/geometry/index/detail/rtree/utilities/print.hpp

Line 194 in f92671b

detail::utilities::print_indexable(os, tr(*it));

[boblukas]

Thanks a lot, I have one last question: if I want to retrieve (not to just print) the value of leaf nodes, how can I do?

To give more context: the R-Tree I'm working with is constructed inserting std::pairs of Box and integers. My goal is to retrieve that pair, but I am not able to find a way to do this. In practice, I'd like to store what is printed on output after executing line

geometry/include/boost/geometry/index/detail/rtree/utilities/print.hpp

Line 194 in f92671b

detail::utilities::print_indexable(os, tr(*it));

[awulkiew]

Elements of leafs are values of the Rtree, so your pair would be *it. tr(*it) would be a box, the same as it->first.