...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Finds values meeting passed predicates e.g. nearest to some Point and/or intersecting some Box.
This query function performs spatial and k-nearest neighbor searches. It allows to pass a set of predicates. Values will be returned only if all predicates are met.
Spatial predicates
Spatial predicates may be generated by one of the functions listed below:
It is possible to negate spatial predicates:
Satisfies predicate
This is a special kind of predicate which allows to pass a user-defined function or function object which checks if Value should be returned by the query. It's generated by:
Nearest predicate
If the nearest predicate is passed a k-nearest neighbor search will be performed. This query will result in returning k values to the output iterator. Only one nearest predicate may be passed to the query. It may be generated by:
Connecting predicates
Predicates may be passed together connected with
.
operator&&()
template<
typename Value
,
typename Parameters
,
typename IndexableGetter
,
typename EqualTo
,
typename Allocator
,
typename Predicates
,
typename OutIter
>
rtree< Value, Parameters, IndexableGetter, EqualTo, Allocator >::size_type
query
(
rtree< Value, Parameters, IndexableGetter, EqualTo, Allocator > const &
tree
,
Predicates const &
predicates
,
OutIter
out_it
)
Type |
Name |
Description |
---|---|---|
|
|
The rtree. |
|
|
Predicates. |
|
|
The output iterator, e.g. generated by std::back_inserter(). |
The number of values found.
// return elements intersecting box bgi::query(tree, bgi::intersects(box), std::back_inserter(result)); // return elements intersecting poly but not within box bgi::query(tree, bgi::intersects(poly) && !bgi::within(box), std::back_inserter(result)); // return elements overlapping box and meeting my_fun value predicate bgi::query(tree, bgi::overlaps(box) && bgi::satisfies(my_fun), std::back_inserter(result)); // return 5 elements nearest to pt and elements are intersecting box bgi::query(tree, bgi::nearest(pt, 5) && bgi::intersects(box), std::back_inserter(result)); // For each found value do_something (it is a type of function object) tree.query(bgi::intersects(box), boost::make_function_output_iterator(do_something()));
If Value copy constructor or copy assignment throws.
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Warning |
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Only one |