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knn queries description added to doc
[SVN r75713]
This commit is contained in:
Adam Wulkiewicz
@@ -31,7 +31,7 @@
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<div><p class="copyright">Copyright © 2008 Federico J. Fernandez</p></div>
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<div><p class="copyright">Copyright © 2011 Adam Wulkiewicz</p></div>
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<div><div class="legalnotice">
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<a name="id798351"></a><p>Use, modification and distribution is subject to the Boost
|
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<a name="id789613"></a><p>Use, modification and distribution is subject to the Boost
|
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Software License, Version 1.0. (See accompanying file
|
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<code class="filename">LICENSE_1_0.txt</code> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</p>
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</div></div>
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@@ -42,13 +42,13 @@
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<dt><span class="section"><a href="index.html#index.intro">Introduction</a></span></dt>
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<dt><span class="section"><a href="index/rtree.html">R-tree</a></span></dt>
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<dd><dl>
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<dt><span class="section"><a href="index/rtree.html#id798399">R-tree creation</a></span></dt>
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<dt><span class="section"><a href="index/rtree.html#id798477">Values, Indexables and default Translator</a></span></dt>
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<dt><span class="section"><a href="index/rtree.html#id798556">Inserting and splitting algorithms</a></span></dt>
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||||
<dt><span class="section"><a href="index/rtree.html#id798596">Inserting and removing Values</a></span></dt>
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||||
<dt><span class="section"><a href="index/rtree.html#id798621">Spatial queries</a></span></dt>
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<dt><span class="section"><a href="index/rtree.html#id798665">Spatial predicates</a></span></dt>
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<dt><span class="section"><a href="index/rtree.html#id798716">Nearest neighbor queries</a></span></dt>
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<dt><span class="section"><a href="index/rtree.html#id789661">R-tree creation</a></span></dt>
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<dt><span class="section"><a href="index/rtree.html#id789748">Values, Indexables and default Translator</a></span></dt>
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<dt><span class="section"><a href="index/rtree.html#id789861">Inserting and splitting algorithms</a></span></dt>
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||||
<dt><span class="section"><a href="index/rtree.html#id789906">Inserting and removing Values</a></span></dt>
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<dt><span class="section"><a href="index/rtree.html#id789931">Spatial queries</a></span></dt>
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<dt><span class="section"><a href="index/rtree.html#id789980">Spatial predicates</a></span></dt>
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<dt><span class="section"><a href="index/rtree.html#id790041">Nearest neighbors queries</a></span></dt>
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</dl></dd>
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</dl>
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</div>
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@@ -25,13 +25,13 @@
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
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<a name="index.rtree"></a>R-tree</h2></div></div></div>
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<div class="toc"><dl>
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<dt><span class="section"><a href="rtree.html#id798399">R-tree creation</a></span></dt>
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<dt><span class="section"><a href="rtree.html#id798477">Values, Indexables and default Translator</a></span></dt>
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<dt><span class="section"><a href="rtree.html#id798556">Inserting and splitting algorithms</a></span></dt>
|
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<dt><span class="section"><a href="rtree.html#id798596">Inserting and removing Values</a></span></dt>
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<dt><span class="section"><a href="rtree.html#id798621">Spatial queries</a></span></dt>
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<dt><span class="section"><a href="rtree.html#id798665">Spatial predicates</a></span></dt>
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<dt><span class="section"><a href="rtree.html#id798716">Nearest neighbor queries</a></span></dt>
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<dt><span class="section"><a href="rtree.html#id789661">R-tree creation</a></span></dt>
|
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<dt><span class="section"><a href="rtree.html#id789748">Values, Indexables and default Translator</a></span></dt>
|
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<dt><span class="section"><a href="rtree.html#id789861">Inserting and splitting algorithms</a></span></dt>
|
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<dt><span class="section"><a href="rtree.html#id789906">Inserting and removing Values</a></span></dt>
|
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<dt><span class="section"><a href="rtree.html#id789931">Spatial queries</a></span></dt>
|
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<dt><span class="section"><a href="rtree.html#id789980">Spatial predicates</a></span></dt>
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<dt><span class="section"><a href="rtree.html#id790041">Nearest neighbors queries</a></span></dt>
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</dl></div>
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<p>
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R-tree is a self-balancing search tree with nodes stored with their axis aligned
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@@ -42,7 +42,7 @@ which may be stored inside the node are user defined.
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</p>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="id798399"></a>R-tree creation</h3></div></div></div>
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<a name="id789661"></a>R-tree creation</h3></div></div></div>
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<p>
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R-tree has 4 parameters:
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</p>
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@@ -56,10 +56,13 @@ rtree<Value, Parameters, Translator, Allocator>
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<code class="computeroutput">Value</code> - type of object which will be stored in the container.
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</li>
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<li class="listitem">
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<code class="computeroutput">Parameters</code> - compile-time parameters, e.g. inserting/splitting algorithm with min and max nodes' elements numbers.
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<code class="computeroutput">Parameters</code> - compile-time parameters, e.g. inserting/splitting
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algorithm with min and max nodes' elements numbers.
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</li>
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<li class="listitem">
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<code class="computeroutput">Translator</code> - type of object translating Value objects to Indexable objects (<code class="computeroutput">Point</code> or <code class="computeroutput">Box</code>) which R-tree can handle.
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<code class="computeroutput">Translator</code> - type of object translating <code class="computeroutput">Value</code> objects
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to <code class="computeroutput">Indexable</code> objects (<code class="computeroutput">Point</code> or <code class="computeroutput">Box</code>) which
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R-tree can handle.
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</li>
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<li class="listitem">
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<code class="computeroutput">Allocator</code> - the allocator.
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@@ -68,7 +71,8 @@ rtree<Value, Parameters, Translator, Allocator>
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<p>
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</p>
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<p>
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In order to create a R-tree object storing values of type <code class="computeroutput">std::pair<Box, int></code> one may use the following code
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In order to create a R-tree object storing values of type
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<code class="computeroutput">std::pair<Box, int></code> one may use the following code
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</p>
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<pre class="programlisting">
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using namespace boost::geometry;
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@@ -80,13 +84,15 @@ index::rtree< Value, index::quadratic<32, 8> > rt;
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="id798477"></a>Values, Indexables and default Translator</h3></div></div></div>
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<a name="id789748"></a>Values, Indexables and default Translator</h3></div></div></div>
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<p>
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R-tree may store Values of any type as long as there is passed the Translator which knows how to interpret
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those Values and extract an object understandable by the R-tree. Those objects are called Indexables
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and they are simply of type adapted to Point or Box concept. Default translator
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<code class="computeroutput">index::translator::def<Value></code> is able to handle <code class="computeroutput">Point</code>, <code class="computeroutput">Box</code>,
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<code class="computeroutput">std::pair<...></code>, pointer, iterator or smart pointer.
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R-tree may store <code class="computeroutput">Value</code>s of any type as long as there is passed
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the <code class="computeroutput">Translator</code> which knows how to interpret those <code class="computeroutput">Value</code>s
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and extract an object understandable by the R-tree. Those objects are called
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<code class="computeroutput">Indexables</code> and they are simply of type adapted to <code class="computeroutput">Point</code>
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or <code class="computeroutput">Box</code> concept. Default translator <code class="computeroutput">index::translator::def<Value></code>
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is able to handle <code class="computeroutput">Point</code>, <code class="computeroutput">Box</code>, <code class="computeroutput">std::pair<...></code>,
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pointer, iterator or smart pointer.
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</p>
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<div class="itemizedlist"><ul class="itemizedlist" type="disc">
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<li class="listitem"><code class="computeroutput">Indexable = Point | Box</code></li>
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@@ -94,7 +100,7 @@ and they are simply of type adapted to Point or Box concept. Default translator
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<li class="listitem"><code class="computeroutput">Value = BasicValue | BasicValue* | Iterator<BasicValue> | SmartPtr<BasicValue></code></li>
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</ul></div>
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<p>
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Examples of Value types:
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Examples of <code class="computeroutput">Value</code> types:
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</p>
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<div class="itemizedlist"><ul class="itemizedlist" type="disc">
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<li class="listitem"><code class="computeroutput">geometry::model::point<...></code></li>
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@@ -107,9 +113,9 @@ Examples of Value types:
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</div>
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<div class="section">
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||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="id798556"></a>Inserting and splitting algorithms</h3></div></div></div>
|
||||
<a name="id789861"></a>Inserting and splitting algorithms</h3></div></div></div>
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<p>
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Values may be inserted to the R-tree in many various ways. Final structure of nodes depends
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<code class="computeroutput">Value</code>s may be inserted to the R-tree in many various ways. Final structure of nodes depends
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on algorithms used in the process, especially nodes' splitting algorithm. Currently, three
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well-known types of R-trees may be created.
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</p>
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@@ -138,7 +144,7 @@ index::rtree< Value, index::rstar<32, 8> > rt;
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="id798596"></a>Inserting and removing Values</h3></div></div></div>
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||||
<a name="id789906"></a>Inserting and removing Values</h3></div></div></div>
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<p>
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Create
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</p>
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@@ -168,10 +174,10 @@ index::remove(rt, v);
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="id798621"></a>Spatial queries</h3></div></div></div>
|
||||
<a name="id789931"></a>Spatial queries</h3></div></div></div>
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<p>
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There are three ways to perform a spatial query. Following queries returns
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Values intersecting some box_region.
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<code class="computeroutput">Value</code>s intersecting some box_region.
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</p>
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<div class="itemizedlist"><ul class="itemizedlist" type="disc">
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<li class="listitem">
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@@ -204,9 +210,9 @@ BOOST_FOREACH(Value &v, rt | index::query_filtered(box_region))
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="id798665"></a>Spatial predicates</h3></div></div></div>
|
||||
<a name="id789980"></a>Spatial predicates</h3></div></div></div>
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<p>
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It is possible to define other relations between queried Values and region/regions
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It is possible to define other relations between queried <code class="computeroutput">Value</code>s and region/regions
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of interest. Names of predicates corresponds to names of Boost.Geometry algorithms.
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</p>
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<pre class="programlisting">
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@@ -245,7 +251,7 @@ rt.query(
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</pre>
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<p>
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There is special predicate <code class="computeroutput">index::value(Fun)</code> taking user-defined function/functor
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which checks if Value should be returned by the query.
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which checks if <code class="computeroutput">Value</code> should be returned by the query.
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</p>
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||||
<pre class="programlisting">
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bool fun(Value const& v)
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@@ -264,8 +270,159 @@ rt.query(
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</div>
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<div class="section">
|
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<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="id798716"></a>Nearest neighbor queries</h3></div></div></div>
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TODO
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<a name="id790041"></a>Nearest neighbors queries</h3></div></div></div>
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<div class="toc"><dl>
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||||
<dt><span class="section"><a href="rtree.html#id790047">k nearest neighbors</a></span></dt>
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<dt><span class="section"><a href="rtree.html#id797757">One nearest neighbor</a></span></dt>
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<dt><span class="section"><a href="rtree.html#id797793">Distances predicates</a></span></dt>
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<dt><span class="section"><a href="rtree.html#id797832">Using spatial predicates</a></span></dt>
|
||||
</dl></div>
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<div class="section">
|
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<div class="titlepage"><div><div><h4 class="title">
|
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<a name="id790047"></a>k nearest neighbors</h4></div></div></div>
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<p>
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There are three ways of performing knn queries. Following queries returns
|
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k <code class="computeroutput">Value</code>s closest to some point in space. For <code class="computeroutput">Box</code>es
|
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<code class="computeroutput">Indexable</code>s closest point of a <code class="computeroutput">Box</code> is taken into
|
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account by default.
|
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</p>
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<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
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<li class="listitem">
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Method call
|
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<pre class="programlisting">
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std::vector<Value> returned_values;
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Point pt(...);
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rt.nearest(pt, k, std::back_inserter(returned_values));
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</pre>
|
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</li>
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<li class="listitem">
|
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Function call
|
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<pre class="programlisting">
|
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std::vector<Value> returned_values;
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Point pt(...);
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index::nearest(rt, pt, k, std::back_inserter(returned_values));
|
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</pre>
|
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</li>
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<li class="listitem">
|
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Use of <code class="computeroutput">operator |</code><pre class="programlisting">
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Point pt(...);
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BOOST_FOREACH(Value &v, rt | index::nearest_filtered(pt, k))
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;// do something with v
|
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</pre>
|
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</li>
|
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</ul></div>
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<p>
|
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</p>
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</div>
|
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<div class="section">
|
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<div class="titlepage"><div><div><h4 class="title">
|
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<a name="id797757"></a>One nearest neighbor</h4></div></div></div>
|
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<p>
|
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Another type of nearest neighbor query is searching for the one closest <code class="computeroutput">Value</code>.
|
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If it is found, 1 is returned by the method or function. This kind of query
|
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has only two forms.
|
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</p>
|
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<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
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<li class="listitem">
|
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Method call
|
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<pre class="programlisting">
|
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Value returned_value;
|
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Point pt(...);
|
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size_t n = rt.nearest(pt, returned_value);
|
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</pre>
|
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</li>
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<li class="listitem">
|
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Function call
|
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<pre class="programlisting">
|
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Value returned_value;
|
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Point pt(...);
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size_t n = index::nearest(rt, pt, returned_value);
|
||||
</pre>
|
||||
</li>
|
||||
</ul></div>
|
||||
<p>
|
||||
</p>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
<a name="id797793"></a>Distances predicates</h4></div></div></div>
|
||||
<p>
|
||||
It is possible to define if calculated distance between query point and <code class="computeroutput">Value</code> should be
|
||||
greater, lesser or between some other distances. Those are called <code class="computeroutput">DistancesPredicate</code>s and
|
||||
may be defined as follows.
|
||||
</p>
|
||||
<pre class="programlisting">
|
||||
std::vector<Value> returned_values;
|
||||
Point pt(...);
|
||||
|
||||
/* default - without bounds */
|
||||
index::nearest(rt, pt, k, std::back_inserter(returned_values));
|
||||
|
||||
/* same as default */
|
||||
index::nearest(rt, index::unbounded(pt), k, std::back_inserter(returned_values));
|
||||
|
||||
/* distance must be greater than or equal to 10 */
|
||||
index::nearest(rt, index::min_bounded(pt, 10), k, std::back_inserter(returned_values));
|
||||
|
||||
/* distance must be lesser than or equal to 500 */
|
||||
index::nearest(rt, index::max_bounded(pt, 500), k, std::back_inserter(returned_values));
|
||||
|
||||
/* distance must be between 10 and 500 */
|
||||
index::nearest(rt, index::bounded(pt, 10, 500), k, std::back_inserter(returned_values));
|
||||
|
||||
</pre>
|
||||
<p>
|
||||
</p>
|
||||
<p>
|
||||
Furthermore, it's possible to define if the closest, furthest or centroidal point of the
|
||||
non-point <code class="computeroutput">Indexable</code> should be taken into account in the routine calculating distance.
|
||||
</p>
|
||||
<pre class="programlisting">
|
||||
std::vector<Value> returned_values;
|
||||
Point pt(...);
|
||||
|
||||
/* default - distance between Indexable's closest point and a query point
|
||||
must be greater than 10 */
|
||||
index::nearest(rt, index::min_bounded(pt, 10), k, std::back_inserter(returned_values));
|
||||
|
||||
/* same as default - distance between Indexable's closest point and a query point
|
||||
must be greater than 10 */
|
||||
index::nearest(rt, index::min_bounded(pt, index::near(10)), k, std::back_inserter(returned_values));
|
||||
|
||||
/* distance between Indexable's furthest point and a query point
|
||||
must be greater than 10 */
|
||||
index::nearest(rt, index::min_bounded(pt, index::far(10)), k, std::back_inserter(returned_values));
|
||||
|
||||
/* distance between Indexable's centroid and a query point
|
||||
must be greater than 10 */
|
||||
index::nearest(rt, index::min_bounded(pt, index::centroid(10)), k, std::back_inserter(returned_values));
|
||||
</pre>
|
||||
<p>
|
||||
</p>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
<a name="id797832"></a>Using spatial predicates</h4></div></div></div>
|
||||
<p>
|
||||
It is possible to use spatial predicates described before in knn queries.
|
||||
</p>
|
||||
<pre class="programlisting">
|
||||
Value returned_value;
|
||||
std::vector<Value> returned_values;
|
||||
|
||||
Point pt(...);
|
||||
Box b(...);
|
||||
|
||||
size_t n1 = rt.nearest(index::bounded(pt, index::far(1), 10), index::intersects(b), returned_value);
|
||||
|
||||
size_t n2 = index::nearest(rt, pt, k, index::within(b), std::back_inserter(returned_values));
|
||||
|
||||
BOOST_FOREACH(Value &v, rt | index::nearest_filtered(pt, k, index::covered_by(b)))
|
||||
;// do something with v
|
||||
</pre>
|
||||
<p>
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
|
||||
175
doc/index.xml
175
doc/index.xml
@@ -68,10 +68,13 @@ rtree<Value, Parameters, Translator, Allocator>
|
||||
<code>Value</code> - type of object which will be stored in the container.
|
||||
</listitem>
|
||||
<listitem>
|
||||
<code>Parameters</code> - compile-time parameters, e.g. inserting/splitting algorithm with min and max nodes' elements numbers.
|
||||
<code>Parameters</code> - compile-time parameters, e.g. inserting/splitting
|
||||
algorithm with min and max nodes' elements numbers.
|
||||
</listitem>
|
||||
<listitem>
|
||||
<code>Translator</code> - type of object translating Value objects to Indexable objects (<code>Point</code> or <code>Box</code>) which R-tree can handle.
|
||||
<code>Translator</code> - type of object translating <code>Value</code> objects
|
||||
to <code>Indexable</code> objects (<code>Point</code> or <code>Box</code>) which
|
||||
R-tree can handle.
|
||||
</listitem>
|
||||
<listitem>
|
||||
<code>Allocator</code> - the allocator.
|
||||
@@ -79,7 +82,8 @@ rtree<Value, Parameters, Translator, Allocator>
|
||||
</itemizedlist>
|
||||
</para>
|
||||
<para>
|
||||
In order to create a R-tree object storing values of type <code>std::pair<Box, int></code> one may use the following code
|
||||
In order to create a R-tree object storing values of type
|
||||
<code>std::pair<Box, int></code> one may use the following code
|
||||
<programlisting>
|
||||
using namespace boost::geometry;
|
||||
typedef std::pair<Box, int> Value;
|
||||
@@ -91,17 +95,19 @@ index::rtree< Value, index::quadratic<32, 8> > rt;
|
||||
<section>
|
||||
<title>Values, Indexables and default Translator</title>
|
||||
<para>
|
||||
R-tree may store Values of any type as long as there is passed the Translator which knows how to interpret
|
||||
those Values and extract an object understandable by the R-tree. Those objects are called Indexables
|
||||
and they are simply of type adapted to Point or Box concept. Default translator
|
||||
<code>index::translator::def<Value></code> is able to handle <code>Point</code>, <code>Box</code>,
|
||||
<code>std::pair<...></code>, pointer, iterator or smart pointer.
|
||||
R-tree may store <code>Value</code>s of any type as long as there is passed
|
||||
the <code>Translator</code> which knows how to interpret those <code>Value</code>s
|
||||
and extract an object understandable by the R-tree. Those objects are called
|
||||
<code>Indexables</code> and they are simply of type adapted to <code>Point</code>
|
||||
or <code>Box</code> concept. Default translator <code>index::translator::def<Value></code>
|
||||
is able to handle <code>Point</code>, <code>Box</code>, <code>std::pair<...></code>,
|
||||
pointer, iterator or smart pointer.
|
||||
<itemizedlist>
|
||||
<listitem><code>Indexable = Point | Box</code></listitem>
|
||||
<listitem><code>BasicValue = Indexable | std::pair<Indexable, T> | std::pair<T, Indexable></code></listitem>
|
||||
<listitem><code>Value = BasicValue | BasicValue* | Iterator<BasicValue> | SmartPtr<BasicValue></code></listitem>
|
||||
</itemizedlist>
|
||||
Examples of Value types:
|
||||
Examples of <code>Value</code> types:
|
||||
<itemizedlist>
|
||||
<listitem><code>geometry::model::point<...></code></listitem>
|
||||
<listitem><code>geometry::model::point_xy<...></code></listitem>
|
||||
@@ -114,7 +120,7 @@ Examples of Value types:
|
||||
<section>
|
||||
<title>Inserting and splitting algorithms</title>
|
||||
<para>
|
||||
Values may be inserted to the R-tree in many various ways. Final structure of nodes depends
|
||||
<code>Value</code>s may be inserted to the R-tree in many various ways. Final structure of nodes depends
|
||||
on algorithms used in the process, especially nodes' splitting algorithm. Currently, three
|
||||
well-known types of R-trees may be created.
|
||||
<itemizedlist>
|
||||
@@ -168,7 +174,7 @@ index::remove(rt, v);
|
||||
<title>Spatial queries</title>
|
||||
<para>
|
||||
There are three ways to perform a spatial query. Following queries returns
|
||||
Values intersecting some box_region.
|
||||
<code>Value</code>s intersecting some box_region.
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
Method call
|
||||
@@ -201,7 +207,7 @@ BOOST_FOREACH(Value &v, rt | index::query_filtered(box_region))
|
||||
<section>
|
||||
<title>Spatial predicates</title>
|
||||
<para>
|
||||
It is possible to define other relations between queried Values and region/regions
|
||||
It is possible to define other relations between queried <code>Value</code>s and region/regions
|
||||
of interest. Names of predicates corresponds to names of Boost.Geometry algorithms.
|
||||
<programlisting>
|
||||
rt.query(box, std::back_inserter(result)); // default case - intersects
|
||||
@@ -232,7 +238,7 @@ rt.query(
|
||||
, std::back_inserter(result));
|
||||
</programlisting>
|
||||
There is special predicate <code>index::value(Fun)</code> taking user-defined function/functor
|
||||
which checks if Value should be returned by the query.
|
||||
which checks if <code>Value</code> should be returned by the query.
|
||||
<programlisting>
|
||||
bool fun(Value const& v)
|
||||
{
|
||||
@@ -249,8 +255,147 @@ rt.query(
|
||||
</section>
|
||||
|
||||
<section>
|
||||
<title>Nearest neighbor queries</title>
|
||||
TODO
|
||||
<title>Nearest neighbors queries</title>
|
||||
|
||||
<section>
|
||||
<title>k nearest neighbors</title>
|
||||
<para>
|
||||
There are three ways of performing knn queries. Following queries returns
|
||||
k <code>Value</code>s closest to some point in space. For <code>Box</code>es
|
||||
<code>Indexable</code>s closest point of a <code>Box</code> is taken into
|
||||
account by default.
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
Method call
|
||||
<programlisting>
|
||||
std::vector<Value> returned_values;
|
||||
Point pt(...);
|
||||
rt.nearest(pt, k, std::back_inserter(returned_values));
|
||||
</programlisting>
|
||||
</listitem>
|
||||
<listitem>
|
||||
Function call
|
||||
<programlisting>
|
||||
std::vector<Value> returned_values;
|
||||
Point pt(...);
|
||||
index::nearest(rt, pt, k, std::back_inserter(returned_values));
|
||||
</programlisting>
|
||||
</listitem>
|
||||
<listitem>
|
||||
Use of <code>operator |</code>
|
||||
<programlisting>
|
||||
Point pt(...);
|
||||
BOOST_FOREACH(Value &v, rt | index::nearest_filtered(pt, k))
|
||||
;// do something with v
|
||||
</programlisting>
|
||||
</listitem>
|
||||
</itemizedlist>
|
||||
</para>
|
||||
</section>
|
||||
|
||||
<section>
|
||||
<title>One nearest neighbor</title>
|
||||
<para>
|
||||
Another type of nearest neighbor query is searching for the one closest <code>Value</code>.
|
||||
If it is found, 1 is returned by the method or function. This kind of query
|
||||
has only two forms.
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
Method call
|
||||
<programlisting>
|
||||
Value returned_value;
|
||||
Point pt(...);
|
||||
size_t n = rt.nearest(pt, returned_value);
|
||||
</programlisting>
|
||||
</listitem>
|
||||
<listitem>
|
||||
Function call
|
||||
<programlisting>
|
||||
Value returned_value;
|
||||
Point pt(...);
|
||||
size_t n = index::nearest(rt, pt, returned_value);
|
||||
</programlisting>
|
||||
</listitem>
|
||||
</itemizedlist>
|
||||
</para>
|
||||
</section>
|
||||
|
||||
<section>
|
||||
<title>Distances predicates</title>
|
||||
<para>
|
||||
It is possible to define if calculated distance between query point and <code>Value</code> should be
|
||||
greater, lesser or between some other distances. Those are called <code>DistancesPredicate</code>s and
|
||||
may be defined as follows.
|
||||
<programlisting>
|
||||
std::vector<Value> returned_values;
|
||||
Point pt(...);
|
||||
|
||||
/* default - without bounds */
|
||||
index::nearest(rt, pt, k, std::back_inserter(returned_values));
|
||||
|
||||
/* same as default */
|
||||
index::nearest(rt, index::unbounded(pt), k, std::back_inserter(returned_values));
|
||||
|
||||
/* distance must be greater than or equal to 10 */
|
||||
index::nearest(rt, index::min_bounded(pt, 10), k, std::back_inserter(returned_values));
|
||||
|
||||
/* distance must be lesser than or equal to 500 */
|
||||
index::nearest(rt, index::max_bounded(pt, 500), k, std::back_inserter(returned_values));
|
||||
|
||||
/* distance must be between 10 and 500 */
|
||||
index::nearest(rt, index::bounded(pt, 10, 500), k, std::back_inserter(returned_values));
|
||||
|
||||
</programlisting>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Furthermore, it's possible to define if the closest, furthest or centroidal point of the
|
||||
non-point <code>Indexable</code> should be taken into account in the routine calculating distance.
|
||||
<programlisting>
|
||||
std::vector<Value> returned_values;
|
||||
Point pt(...);
|
||||
|
||||
/* default - distance between Indexable's closest point and a query point
|
||||
must be greater than 10 */
|
||||
index::nearest(rt, index::min_bounded(pt, 10), k, std::back_inserter(returned_values));
|
||||
|
||||
/* same as default - distance between Indexable's closest point and a query point
|
||||
must be greater than 10 */
|
||||
index::nearest(rt, index::min_bounded(pt, index::near(10)), k, std::back_inserter(returned_values));
|
||||
|
||||
/* distance between Indexable's furthest point and a query point
|
||||
must be greater than 10 */
|
||||
index::nearest(rt, index::min_bounded(pt, index::far(10)), k, std::back_inserter(returned_values));
|
||||
|
||||
/* distance between Indexable's centroid and a query point
|
||||
must be greater than 10 */
|
||||
index::nearest(rt, index::min_bounded(pt, index::centroid(10)), k, std::back_inserter(returned_values));
|
||||
</programlisting>
|
||||
</para>
|
||||
|
||||
</section>
|
||||
|
||||
<section>
|
||||
<title>Using spatial predicates</title>
|
||||
<para>
|
||||
It is possible to use spatial predicates described before in knn queries.
|
||||
<programlisting>
|
||||
Value returned_value;
|
||||
std::vector<Value> returned_values;
|
||||
|
||||
Point pt(...);
|
||||
Box b(...);
|
||||
|
||||
size_t n1 = rt.nearest(index::bounded(pt, index::far(1), 10), index::intersects(b), returned_value);
|
||||
|
||||
size_t n2 = index::nearest(rt, pt, k, index::within(b), std::back_inserter(returned_values));
|
||||
|
||||
BOOST_FOREACH(Value &v, rt | index::nearest_filtered(pt, k, index::covered_by(b)))
|
||||
;// do something with v
|
||||
</programlisting>
|
||||
</para>
|
||||
</section>
|
||||
|
||||
</section>
|
||||
|
||||
</section>
|
||||
|
||||
Reference in New Issue
Block a user