1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Std transform</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. Boost.Icl"> 8<link rel="up" href="../examples.html" title="Examples"> 9<link rel="prev" href="std_copy.html" title="Std copy"> 10<link rel="next" href="custom_interval.html" title="Custom interval"> 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="../../../../../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="std_copy.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../examples.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="custom_interval.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="boost_icl.examples.std_transform"></a><a class="link" href="std_transform.html" title="Std transform">Std transform</a> 28</h3></div></div></div> 29<p> 30 Instead of writing loops, the standard algorithm <a href="http://www.cplusplus.com/reference/algorithm/transform/" target="_top"><code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">transform</span></code></a> 31 can be used to fill interval containers from std containers of user defined 32 objects. We need a function, that maps the <span class="emphasis"><em>user defined object</em></span> 33 into the <span class="emphasis"><em>segement type</em></span> of an interval map or the <span class="emphasis"><em>interval 34 type</em></span> of an interval set. Based on that we can use <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">transform</span></code> 35 with an <code class="computeroutput"><span class="identifier">icl</span><span class="special">::</span><span class="identifier">inserter</span></code> or <code class="computeroutput"><span class="identifier">icl</span><span class="special">::</span><span class="identifier">adder</span></code> 36 to transform the user objects into interval containers. 37 </p> 38<p> 39</p> 40<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> 41<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> 42<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">algorithm</span><span class="special">></span> 43<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">icl</span><span class="special">/</span><span class="identifier">split_interval_map</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 44<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">icl</span><span class="special">/</span><span class="identifier">separate_interval_set</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 45 46<span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">std</span><span class="special">;</span> 47<span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">;</span> 48<span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">icl</span><span class="special">;</span> 49 50<span class="comment">// Suppose we are working with a class called MyObject, containing some</span> 51<span class="comment">// information about interval bounds e.g. _from, _to and some data members</span> 52<span class="comment">// that carry associated information like e.g. _value.</span> 53<span class="keyword">class</span> <span class="identifier">MyObject</span> 54<span class="special">{</span> 55<span class="keyword">public</span><span class="special">:</span> 56 <span class="identifier">MyObject</span><span class="special">(){}</span> 57 <span class="identifier">MyObject</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">from</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">to</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">value</span><span class="special">):</span> <span class="identifier">_from</span><span class="special">(</span><span class="identifier">from</span><span class="special">),</span> <span class="identifier">_to</span><span class="special">(</span><span class="identifier">to</span><span class="special">),</span> <span class="identifier">_value</span><span class="special">(</span><span class="identifier">value</span><span class="special">){}</span> 58 <span class="keyword">int</span> <span class="identifier">from</span><span class="special">()</span><span class="keyword">const</span> <span class="special">{</span><span class="keyword">return</span> <span class="identifier">_from</span><span class="special">;}</span> 59 <span class="keyword">int</span> <span class="identifier">to</span><span class="special">()</span><span class="keyword">const</span> <span class="special">{</span><span class="keyword">return</span> <span class="identifier">_to</span><span class="special">;}</span> 60 <span class="keyword">int</span> <span class="identifier">value</span><span class="special">()</span><span class="keyword">const</span><span class="special">{</span><span class="keyword">return</span> <span class="identifier">_value</span><span class="special">;}</span> 61<span class="keyword">private</span><span class="special">:</span> 62 <span class="keyword">int</span> <span class="identifier">_from</span><span class="special">;</span> 63 <span class="keyword">int</span> <span class="identifier">_to</span><span class="special">;</span> 64 <span class="keyword">int</span> <span class="identifier">_value</span><span class="special">;</span> 65<span class="special">};</span> 66 67<span class="comment">// ... in order to use the std::transform algorithm to fill</span> 68<span class="comment">// interval maps with MyObject data we need a function</span> 69<span class="comment">// 'to_segment' that maps an object of type MyObject into</span> 70<span class="comment">// the value type to the interval map we want to tranform to ...</span> 71<span class="identifier">pair</span><span class="special"><</span><span class="identifier">discrete_interval</span><span class="special"><</span><span class="keyword">int</span><span class="special">>,</span> <span class="keyword">int</span><span class="special">></span> <span class="identifier">to_segment</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">MyObject</span><span class="special">&</span> <span class="identifier">myObj</span><span class="special">)</span> 72<span class="special">{</span> 73 <span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span> <span class="identifier">discrete_interval</span><span class="special"><</span><span class="keyword">int</span><span class="special">>,</span> <span class="keyword">int</span> <span class="special">></span> 74 <span class="special">(</span><span class="identifier">discrete_interval</span><span class="special"><</span><span class="keyword">int</span><span class="special">>::</span><span class="identifier">closed</span><span class="special">(</span><span class="identifier">myObj</span><span class="special">.</span><span class="identifier">from</span><span class="special">(),</span> <span class="identifier">myObj</span><span class="special">.</span><span class="identifier">to</span><span class="special">()),</span> <span class="identifier">myObj</span><span class="special">.</span><span class="identifier">value</span><span class="special">());</span> 75<span class="special">}</span> 76 77<span class="comment">// ... there may be another function that returns the interval</span> 78<span class="comment">// of an object only</span> 79<span class="identifier">discrete_interval</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">to_interval</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">MyObject</span><span class="special">&</span> <span class="identifier">myObj</span><span class="special">)</span> 80<span class="special">{</span> 81 <span class="keyword">return</span> <span class="identifier">discrete_interval</span><span class="special"><</span><span class="keyword">int</span><span class="special">>::</span><span class="identifier">closed</span><span class="special">(</span><span class="identifier">myObj</span><span class="special">.</span><span class="identifier">from</span><span class="special">(),</span> <span class="identifier">myObj</span><span class="special">.</span><span class="identifier">to</span><span class="special">());</span> 82<span class="special">}</span> 83 84 85<span class="comment">// ... make_object computes a sequence of objects to test.</span> 86<span class="identifier">vector</span><span class="special"><</span><span class="identifier">MyObject</span><span class="special">></span> <span class="identifier">make_objects</span><span class="special">()</span> 87<span class="special">{</span> 88 <span class="identifier">vector</span><span class="special"><</span><span class="identifier">MyObject</span><span class="special">></span> <span class="identifier">object_vec</span><span class="special">;</span> 89 <span class="identifier">object_vec</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="identifier">MyObject</span><span class="special">(</span><span class="number">2</span><span class="special">,</span><span class="number">3</span><span class="special">,</span><span class="number">1</span><span class="special">));</span> 90 <span class="identifier">object_vec</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="identifier">MyObject</span><span class="special">(</span><span class="number">4</span><span class="special">,</span><span class="number">4</span><span class="special">,</span><span class="number">1</span><span class="special">));</span> 91 <span class="identifier">object_vec</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="identifier">MyObject</span><span class="special">(</span><span class="number">1</span><span class="special">,</span><span class="number">2</span><span class="special">,</span><span class="number">1</span><span class="special">));</span> 92 <span class="keyword">return</span> <span class="identifier">object_vec</span><span class="special">;</span> 93<span class="special">}</span> 94 95<span class="comment">// ... show_objects displays the sequence of input objects.</span> 96<span class="keyword">void</span> <span class="identifier">show_objects</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">vector</span><span class="special"><</span><span class="identifier">MyObject</span><span class="special">>&</span> <span class="identifier">objects</span><span class="special">)</span> 97<span class="special">{</span> 98 <span class="identifier">vector</span><span class="special"><</span><span class="identifier">MyObject</span><span class="special">>::</span><span class="identifier">const_iterator</span> <span class="identifier">iter</span> <span class="special">=</span> <span class="identifier">objects</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> 99 <span class="keyword">while</span><span class="special">(</span><span class="identifier">iter</span> <span class="special">!=</span> <span class="identifier">objects</span><span class="special">.</span><span class="identifier">end</span><span class="special">())</span> 100 <span class="special">{</span> 101 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"(["</span> <span class="special"><<</span> <span class="identifier">iter</span><span class="special">-></span><span class="identifier">from</span><span class="special">()</span> <span class="special"><<</span> <span class="string">","</span> <span class="special"><<</span> <span class="identifier">iter</span><span class="special">-></span><span class="identifier">to</span><span class="special">()</span> <span class="special"><<</span> <span class="string">"],"</span> 102 <span class="special"><<</span> <span class="identifier">iter</span><span class="special">-></span><span class="identifier">value</span><span class="special">()</span> <span class="special"><<</span> <span class="string">")"</span><span class="special">;</span> 103 <span class="special">++</span><span class="identifier">iter</span><span class="special">;</span> 104 <span class="special">}</span> 105<span class="special">}</span> 106 107 108<span class="keyword">void</span> <span class="identifier">std_transform</span><span class="special">()</span> 109<span class="special">{</span> 110 <span class="comment">// This time we want to transform objects into a splitting interval map:</span> 111 <span class="identifier">split_interval_map</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">segmap</span><span class="special">;</span> 112 <span class="identifier">vector</span><span class="special"><</span><span class="identifier">MyObject</span><span class="special">></span> <span class="identifier">myObjects</span> <span class="special">=</span> <span class="identifier">make_objects</span><span class="special">();</span> 113 114 <span class="comment">// Display the input</span> 115 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"input sequence: "</span><span class="special">;</span> <span class="identifier">show_objects</span><span class="special">(</span><span class="identifier">myObjects</span><span class="special">);</span> <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"\n\n"</span><span class="special">;</span> 116 117 <span class="comment">// Use an icl::inserter to fill the interval map via inserts</span> 118 <span class="identifier">std</span><span class="special">::</span><span class="identifier">transform</span><span class="special">(</span><span class="identifier">myObjects</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">myObjects</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> 119 <span class="identifier">icl</span><span class="special">::</span><span class="identifier">inserter</span><span class="special">(</span><span class="identifier">segmap</span><span class="special">,</span> <span class="identifier">segmap</span><span class="special">.</span><span class="identifier">end</span><span class="special">()),</span> 120 <span class="identifier">to_segment</span><span class="special">);</span> 121 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"icl::inserting: "</span> <span class="special"><<</span> <span class="identifier">segmap</span> <span class="special"><<</span> <span class="identifier">endl</span><span class="special">;</span> 122 <span class="identifier">segmap</span><span class="special">.</span><span class="identifier">clear</span><span class="special">();</span> 123 124 <span class="comment">// In order to compute aggregation results on associated values, we</span> 125 <span class="comment">// usually want to use an icl::adder instead of an std or icl::inserter</span> 126 <span class="identifier">std</span><span class="special">::</span><span class="identifier">transform</span><span class="special">(</span><span class="identifier">myObjects</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">myObjects</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> 127 <span class="identifier">icl</span><span class="special">::</span><span class="identifier">adder</span><span class="special">(</span><span class="identifier">segmap</span><span class="special">,</span> <span class="identifier">segmap</span><span class="special">.</span><span class="identifier">end</span><span class="special">()),</span> 128 <span class="identifier">to_segment</span><span class="special">);</span> 129 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"icl::adding : "</span> <span class="special"><<</span> <span class="identifier">segmap</span> <span class="special"><<</span> <span class="string">"\n\n"</span><span class="special">;</span> 130 131 <span class="identifier">separate_interval_set</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">segset</span><span class="special">;</span> 132 <span class="identifier">std</span><span class="special">::</span><span class="identifier">transform</span><span class="special">(</span><span class="identifier">myObjects</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">myObjects</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> 133 <span class="identifier">icl</span><span class="special">::</span><span class="identifier">adder</span> <span class="special">(</span><span class="identifier">segset</span><span class="special">,</span> <span class="identifier">segset</span><span class="special">.</span><span class="identifier">end</span><span class="special">()),</span> 134 <span class="comment">// could be a icl::inserter(segset, segset.end()), here: same effect </span> 135 <span class="identifier">to_interval</span><span class="special">);</span> 136 137 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Using std::transform to fill a separate_interval_set:\n\n"</span><span class="special">;</span> 138 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"icl::adding : "</span> <span class="special"><<</span> <span class="identifier">segset</span> <span class="special"><<</span> <span class="string">"\n\n"</span><span class="special">;</span> 139<span class="special">}</span> 140 141 142<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> 143<span class="special">{</span> 144 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">">> Interval Container Library: Example std_transform.cpp <<\n"</span><span class="special">;</span> 145 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"------------------------------------------------------------\n"</span><span class="special">;</span> 146 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Using std::transform to fill a split_interval_map:\n\n"</span><span class="special">;</span> 147 148 <span class="identifier">std_transform</span><span class="special">();</span> 149 <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> 150<span class="special">}</span> 151 152<span class="comment">// Program output:</span> 153<span class="comment">/*---------------------------------------------------------- 154>> Interval Container Library: Example std_transform.cpp << 155------------------------------------------------------------ 156Using std::transform to fill a split_interval_map: 157 158input sequence: ([2,3],1)([4,4],1)([1,2],1) 159 160icl::inserting: {([1,2)->1)([2,3]->1)([4,4]->1)} 161icl::adding : {([1,2)->1)([2,2]->2)((2,3]->1)([4,4]->1)} 162 163Using std::transform to fill a separate_interval_set: 164 165icl::adding : {[1,3][4,4]} 166----------------------------------------------------------*/</span> 167</pre> 168<p> 169 </p> 170<p> 171 To get clear about the different behaviors of interval containers in the 172 example, you may want to refer to the section about <a class="link" href="../../index.html#boost_icl.introduction.interval_combining_styles" title="Interval Combining Styles">interval 173 combining styles</a> that uses the same data. 174 </p> 175</div> 176<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 177<td align="left"></td> 178<td align="right"><div class="copyright-footer">Copyright © 2007-2010 Joachim 179 Faulhaber<br>Copyright © 1999-2006 Cortex Software 180 GmbH<p> 181 Distributed under the Boost Software License, Version 1.0. (See accompanying 182 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>) 183 </p> 184</div></td> 185</tr></table> 186<hr> 187<div class="spirit-nav"> 188<a accesskey="p" href="std_copy.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../examples.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="custom_interval.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 189</div> 190</body> 191</html> 192
