1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Quick Start</title> 5<link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../index.html" title="Chapter 1. Geometry"> 8<link rel="up" href="../spatial_indexes.html" title="Spatial Indexes"> 9<link rel="prev" href="introduction.html" title="Introduction"> 10<link rel="next" href="creation_and_modification.html" title="Creation and Modification"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="introduction.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../spatial_indexes.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="creation_and_modification.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h3 class="title"> 27<a name="geometry.spatial_indexes.rtree_quickstart"></a><a class="link" href="rtree_quickstart.html" title="Quick Start">Quick Start</a> 28</h3></div></div></div> 29<p> 30 This Quick Start section shows simple way to creating a typical R-tree and 31 perform spatial query. 32 </p> 33<p> 34 The code below assumes that following files are included and namespaces used. 35 </p> 36<p> 37</p> 38<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> 39<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> 40<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> 41 42<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> 43 44<span class="comment">// to store queries results</span> 45<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> 46 47<span class="comment">// just for output</span> 48<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> 49<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> 50 51<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> 52<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> 53</pre> 54<p> 55 </p> 56<p> 57 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> 58 will be some identifier of a complex <code class="computeroutput"><span class="identifier">Geometry</span></code> 59 stored in other container, e.g. index type of a <code class="computeroutput"><span class="identifier">Polygon</span></code> 60 stored in the vector or an iterator of list of <code class="computeroutput"><span class="identifier">Ring</span></code>s. 61 To keep it simple to define <code class="computeroutput"><span class="identifier">Value</span></code> 62 we will use predefined Box and unsigned int. 63 </p> 64<p> 65</p> 66<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> 67<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> 68<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> 69</pre> 70<p> 71 </p> 72<p> 73 R-tree may be created using various algorithm and parameters. You should 74 choose the algorithm you'll find the best for your purpose. In this example 75 we will use quadratic algorithm. Parameters are passed as template parameters. 76 Maximum number of elements in nodes is set to 16. 77 </p> 78<p> 79</p> 80<pre class="programlisting"><span class="comment">// create the rtree using default constructor</span> 81<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> 82</pre> 83<p> 84 </p> 85<p> 86 Typically <code class="computeroutput"><span class="identifier">Value</span></code>s will be 87 generated in a loop from e.g. <code class="computeroutput"><span class="identifier">Polygon</span></code>s 88 stored in some other container. In this case <code class="computeroutput"><span class="identifier">Box</span></code> 89 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 90 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> 91 method. 92 </p> 93<p> 94</p> 95<pre class="programlisting"><span class="comment">// create some values</span> 96<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> 97<span class="special">{</span> 98 <span class="comment">// create a box</span> 99 <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> 100 <span class="comment">// insert new value</span> 101 <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> 102<span class="special">}</span> 103</pre> 104<p> 105 </p> 106<p> 107 There are various types of spatial queries that may be performed, they can 108 be even combined together in one call. For simplicity, we use the default 109 one. The following query return values intersecting a box. The sequence of 110 <code class="computeroutput"><span class="identifier">Values</span></code> in the result is not 111 specified. 112 </p> 113<p> 114</p> 115<pre class="programlisting"><span class="comment">// find values intersecting some area defined by a box</span> 116<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> 117<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> 118<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> 119</pre> 120<p> 121 </p> 122<p> 123 Other type of query is k-nearest neighbor search. It returns some number 124 of values nearest to some point in space. The default knn query may be performed 125 as follows. The sequence of <code class="computeroutput"><span class="identifier">Values</span></code> 126 in the result is not specified. 127 </p> 128<p> 129</p> 130<pre class="programlisting"><span class="comment">// find 5 nearest values to a point</span> 131<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> 132<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> 133</pre> 134<p> 135 </p> 136<p> 137 At the end we'll print results. 138 </p> 139<p> 140</p> 141<pre class="programlisting"><span class="comment">// display results</span> 142<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> 143<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> 144<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> 145<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> 146 <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> 147 148<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> 149<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> 150<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> 151<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> 152 <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> 153</pre> 154<p> 155 </p> 156<h4> 157<a name="geometry.spatial_indexes.rtree_quickstart.h0"></a> 158 <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> 159 </h4> 160<p> 161 More information about the R-tree implementation, other algorithms and queries 162 may be found in other parts of this documentation. 163 </p> 164</div> 165<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 166<td align="left"></td> 167<td align="right"><div class="copyright-footer">Copyright © 2009-2019 Barend Gehrels, Bruno Lalande, Mateusz Loskot, Adam 168 Wulkiewicz, Oracle and/or its affiliates<p> 169 Distributed under the Boost Software License, Version 1.0. (See accompanying 170 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>) 171 </p> 172</div></td> 173</tr></table> 174<hr> 175<div class="spirit-nav"> 176<a accesskey="p" href="introduction.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../spatial_indexes.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="creation_and_modification.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 177</div> 178</body> 179</html> 180
