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| <div class="section"> |
| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="geometry.spatial_indexes.rtree_quickstart"></a><a class="link" href="rtree_quickstart.html" title="Quick Start">Quick Start</a> |
| </h3></div></div></div> |
| <p> |
| This Quick Start section shows simple way to creating a typical R-tree and |
| perform spatial query. |
| </p> |
| <p> |
| The code below assumes that following files are included and namespaces used. |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">point</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">box</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">index</span><span class="special">/</span><span class="identifier">rtree</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| |
| <span class="comment">// to store queries results</span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> |
| |
| <span class="comment">// just for output</span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">foreach</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| |
| <span class="keyword">namespace</span> <span class="identifier">bg</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">;</span> |
| <span class="keyword">namespace</span> <span class="identifier">bgi</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">index</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Typically you'll store e.g. <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">Box</span><span class="special">,</span> <span class="identifier">MyGeometryId</span><span class="special">></span></code> in the R-tree. <code class="computeroutput"><span class="identifier">MyGeometryId</span></code> |
| will be some identifier of a complex <code class="computeroutput"><span class="identifier">Geometry</span></code> |
| stored in other container, e.g. index type of a <code class="computeroutput"><span class="identifier">Polygon</span></code> |
| stored in the vector or an iterator of list of <code class="computeroutput"><span class="identifier">Ring</span></code>s. |
| To keep it simple to define <code class="computeroutput"><span class="identifier">Value</span></code> |
| we will use predefined Box and unsigned int. |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">point</span><span class="special"><</span><span class="keyword">float</span><span class="special">,</span> <span class="number">2</span><span class="special">,</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">cs</span><span class="special">::</span><span class="identifier">cartesian</span><span class="special">></span> <span class="identifier">point</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">box</span><span class="special"><</span><span class="identifier">point</span><span class="special">></span> <span class="identifier">box</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">box</span><span class="special">,</span> <span class="keyword">unsigned</span><span class="special">></span> <span class="identifier">value</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| R-tree may be created using various algorithm and parameters. You should |
| choose the algorithm you'll find the best for your purpose. In this example |
| we will use quadratic algorithm. Parameters are passed as template parameters. |
| Maximum number of elements in nodes is set to 16. |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="comment">// create the rtree using default constructor</span> |
| <span class="identifier">bgi</span><span class="special">::</span><span class="identifier">rtree</span><span class="special"><</span> <span class="identifier">value</span><span class="special">,</span> <span class="identifier">bgi</span><span class="special">::</span><span class="identifier">quadratic</span><span class="special"><</span><span class="number">16</span><span class="special">></span> <span class="special">></span> <span class="identifier">rtree</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Typically <code class="computeroutput"><span class="identifier">Value</span></code>s will be |
| generated in a loop from e.g. <code class="computeroutput"><span class="identifier">Polygon</span></code>s |
| stored in some other container. In this case <code class="computeroutput"><span class="identifier">Box</span></code> |
| objects will probably be created with <code class="computeroutput"><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">envelope</span><span class="special">()</span></code> function. But to keep it simple lets just |
| generate some boxes manually and insert them into the R-tree by using <code class="computeroutput"><span class="identifier">insert</span><span class="special">()</span></code> |
| method. |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="comment">// create some values</span> |
| <span class="keyword">for</span> <span class="special">(</span> <span class="keyword">unsigned</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span> <span class="special">;</span> <span class="identifier">i</span> <span class="special"><</span> <span class="number">10</span> <span class="special">;</span> <span class="special">++</span><span class="identifier">i</span> <span class="special">)</span> |
| <span class="special">{</span> |
| <span class="comment">// create a box</span> |
| <span class="identifier">box</span> <span class="identifier">b</span><span class="special">(</span><span class="identifier">point</span><span class="special">(</span><span class="identifier">i</span> <span class="special">+</span> <span class="number">0.0f</span><span class="special">,</span> <span class="identifier">i</span> <span class="special">+</span> <span class="number">0.0f</span><span class="special">),</span> <span class="identifier">point</span><span class="special">(</span><span class="identifier">i</span> <span class="special">+</span> <span class="number">0.5f</span><span class="special">,</span> <span class="identifier">i</span> <span class="special">+</span> <span class="number">0.5f</span><span class="special">));</span> |
| <span class="comment">// insert new value</span> |
| <span class="identifier">rtree</span><span class="special">.</span><span class="identifier">insert</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">i</span><span class="special">));</span> |
| <span class="special">}</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| There are various types of spatial queries that may be performed, they can |
| be even combined together in one call. For simplicity, we use the default |
| one. The following query return values intersecting a box. The sequence of |
| <code class="computeroutput"><span class="identifier">Values</span></code> in the result is not |
| specified. |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="comment">// find values intersecting some area defined by a box</span> |
| <span class="identifier">box</span> <span class="identifier">query_box</span><span class="special">(</span><span class="identifier">point</span><span class="special">(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">),</span> <span class="identifier">point</span><span class="special">(</span><span class="number">5</span><span class="special">,</span> <span class="number">5</span><span class="special">));</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">value</span><span class="special">></span> <span class="identifier">result_s</span><span class="special">;</span> |
| <span class="identifier">rtree</span><span class="special">.</span><span class="identifier">query</span><span class="special">(</span><span class="identifier">bgi</span><span class="special">::</span><span class="identifier">intersects</span><span class="special">(</span><span class="identifier">query_box</span><span class="special">),</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">back_inserter</span><span class="special">(</span><span class="identifier">result_s</span><span class="special">));</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Other type of query is k-nearest neighbor search. It returns some number |
| of values nearest to some point in space. The default knn query may be performed |
| as follows. The sequence of <code class="computeroutput"><span class="identifier">Values</span></code> |
| in the result is not specified. |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="comment">// find 5 nearest values to a point</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">value</span><span class="special">></span> <span class="identifier">result_n</span><span class="special">;</span> |
| <span class="identifier">rtree</span><span class="special">.</span><span class="identifier">query</span><span class="special">(</span><span class="identifier">bgi</span><span class="special">::</span><span class="identifier">nearest</span><span class="special">(</span><span class="identifier">point</span><span class="special">(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">),</span> <span class="number">5</span><span class="special">),</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">back_inserter</span><span class="special">(</span><span class="identifier">result_n</span><span class="special">));</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| At the end we'll print results. |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="comment">// display results</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"spatial query box:"</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">wkt</span><span class="special"><</span><span class="identifier">box</span><span class="special">>(</span><span class="identifier">query_box</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"spatial query result:"</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="identifier">BOOST_FOREACH</span><span class="special">(</span><span class="identifier">value</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">v</span><span class="special">,</span> <span class="identifier">result_s</span><span class="special">)</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">wkt</span><span class="special"><</span><span class="identifier">box</span><span class="special">>(</span><span class="identifier">v</span><span class="special">.</span><span class="identifier">first</span><span class="special">)</span> <span class="special"><<</span> <span class="string">" - "</span> <span class="special"><<</span> <span class="identifier">v</span><span class="special">.</span><span class="identifier">second</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"knn query point:"</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">wkt</span><span class="special"><</span><span class="identifier">point</span><span class="special">>(</span><span class="identifier">point</span><span class="special">(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">))</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"knn query result:"</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="identifier">BOOST_FOREACH</span><span class="special">(</span><span class="identifier">value</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">v</span><span class="special">,</span> <span class="identifier">result_n</span><span class="special">)</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">wkt</span><span class="special"><</span><span class="identifier">box</span><span class="special">>(</span><span class="identifier">v</span><span class="special">.</span><span class="identifier">first</span><span class="special">)</span> <span class="special"><<</span> <span class="string">" - "</span> <span class="special"><<</span> <span class="identifier">v</span><span class="special">.</span><span class="identifier">second</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <h4> |
| <a name="geometry.spatial_indexes.rtree_quickstart.h0"></a> |
| <span class="phrase"><a name="geometry.spatial_indexes.rtree_quickstart.more"></a></span><a class="link" href="rtree_quickstart.html#geometry.spatial_indexes.rtree_quickstart.more">More</a> |
| </h4> |
| <p> |
| More information about the R-tree implementation, other algorithms and queries |
| may be found in other parts of this documentation. |
| </p> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2009-2015 Barend Gehrels, Bruno Lalande, |
| Mateusz Loskot, Adam Wulkiewicz, Oracle and/or its affiliates<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt 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> |
| </div></td> |
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