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25 | <div class="section boost_icl_examples_std_transform" lang="en"> | |
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 | <p> | |
41 | ||
42 | </p> | |
43 | <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> | |
44 | <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> | |
45 | <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">algorithm</span><span class="special">></span> | |
46 | <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> | |
47 | <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> | |
48 | ||
49 | <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">std</span><span class="special">;</span> | |
50 | <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">;</span> | |
51 | <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> | |
52 | ||
53 | <span class="comment">// Suppose we are working with a class called MyObject, containing some | |
54 | </span><span class="comment">// information about interval bounds e.g. _from, _to and some data members | |
55 | </span><span class="comment">// that carry associated information like e.g. _value. | |
56 | </span><span class="keyword">class</span> <span class="identifier">MyObject</span> | |
57 | <span class="special">{</span> | |
58 | <span class="keyword">public</span><span class="special">:</span> | |
59 | <span class="identifier">MyObject</span><span class="special">(){}</span> | |
60 | <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> | |
61 | <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> | |
62 | <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> | |
63 | <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> | |
64 | <span class="keyword">private</span><span class="special">:</span> | |
65 | <span class="keyword">int</span> <span class="identifier">_from</span><span class="special">;</span> | |
66 | <span class="keyword">int</span> <span class="identifier">_to</span><span class="special">;</span> | |
67 | <span class="keyword">int</span> <span class="identifier">_value</span><span class="special">;</span> | |
68 | <span class="special">};</span> | |
69 | ||
70 | <span class="comment">// ... in order to use the std::transform algorithm to fill | |
71 | </span><span class="comment">// interval maps with MyObject data we need a function | |
72 | </span><span class="comment">// 'to_segment' that maps an object of type MyObject into | |
73 | </span><span class="comment">// the value type to the interval map we want to tranform to ... | |
74 | </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> <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> | |
75 | <span class="special">{</span> | |
76 | <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> | |
77 | <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> | |
78 | <span class="special">}</span> | |
79 | ||
80 | <span class="comment">// ... there may be another function that returns the interval | |
81 | </span><span class="comment">// of an object only | |
82 | </span><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> | |
83 | <span class="special">{</span> | |
84 | <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> | |
85 | <span class="special">}</span> | |
86 | ||
87 | ||
88 | <span class="comment">// ... make_object computes a sequence of objects to test. | |
89 | </span><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> | |
90 | <span class="special">{</span> | |
91 | <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> | |
92 | <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> | |
93 | <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> | |
94 | <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> | |
95 | <span class="keyword">return</span> <span class="identifier">object_vec</span><span class="special">;</span> | |
96 | <span class="special">}</span> | |
97 | ||
98 | <span class="comment">// ... show_objects displays the sequence of input objects. | |
99 | </span><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> | |
100 | <span class="special">{</span> | |
101 | <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> | |
102 | <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> | |
103 | <span class="special">{</span> | |
104 | <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> | |
105 | <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> | |
106 | <span class="special">++</span><span class="identifier">iter</span><span class="special">;</span> | |
107 | <span class="special">}</span> | |
108 | <span class="special">}</span> | |
109 | ||
110 | ||
111 | <span class="keyword">void</span> <span class="identifier">std_transform</span><span class="special">()</span> | |
112 | <span class="special">{</span> | |
113 | <span class="comment">// This time we want to transform objects into a splitting interval map: | |
114 | </span> <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> | |
115 | <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> | |
116 | ||
117 | <span class="comment">// Display the input | |
118 | </span> <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> | |
119 | ||
120 | <span class="comment">// Use an icl::inserter to fill the interval map via inserts | |
121 | </span> <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> | |
122 | <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> | |
123 | <span class="identifier">to_segment</span><span class="special">);</span> | |
124 | <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> | |
125 | <span class="identifier">segmap</span><span class="special">.</span><span class="identifier">clear</span><span class="special">();</span> | |
126 | ||
127 | <span class="comment">// In order to compute aggregation results on associated values, we | |
128 | </span> <span class="comment">// usually want to use an icl::adder instead of an std or icl::inserter | |
129 | </span> <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> | |
130 | <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> | |
131 | <span class="identifier">to_segment</span><span class="special">);</span> | |
132 | <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> | |
133 | ||
134 | <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> | |
135 | <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> | |
136 | <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> | |
137 | <span class="comment">// could be a icl::inserter(segset, segset.end()), here: same effect | |
138 | </span> <span class="identifier">to_interval</span><span class="special">);</span> | |
139 | ||
140 | <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> | |
141 | <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> | |
142 | <span class="special">}</span> | |
143 | ||
144 | ||
145 | <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> | |
146 | <span class="special">{</span> | |
147 | <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> | |
148 | <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"------------------------------------------------------------\n"</span><span class="special">;</span> | |
149 | <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> | |
150 | ||
151 | <span class="identifier">std_transform</span><span class="special">();</span> | |
152 | <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> | |
153 | <span class="special">}</span> | |
154 | ||
155 | <span class="comment">// Program output: | |
156 | </span><span class="comment">/*---------------------------------------------------------- | |
157 | >> Interval Container Library: Example std_transform.cpp << | |
158 | ------------------------------------------------------------ | |
159 | Using std::transform to fill a split_interval_map: | |
160 | ||
161 | input sequence: ([2,3],1)([4,4],1)([1,2],1) | |
162 | ||
163 | icl::inserting: {([1,2)->1)([2,3]->1)([4,4]->1)} | |
164 | icl::adding : {([1,2)->1)([2,2]->2)((2,3]->1)([4,4]->1)} | |
165 | ||
166 | Using std::transform to fill a separate_interval_set: | |
167 | ||
168 | icl::adding : {[1,3][4,4]} | |
169 | ----------------------------------------------------------*/</span> | |
170 | </pre> | |
171 | <p> | |
172 | </p> | |
173 | <p> | |
174 | </p> | |
175 | <p> | |
176 | To get clear about the different behaviors of interval containers in the | |
177 | 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 | |
178 | combining styles</a> that uses the same data. | |
179 | </p> | |
180 | </div> | |
181 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
182 | <td align="left"></td> | |
183 | <td align="right"><div class="copyright-footer">Copyright © 2007 -2010 Joachim Faulhaber<br>Copyright © 1999 -2006 Cortex Software GmbH<p> | |
184 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
185 | 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>) | |
186 | </p> | |
187 | </div></td> | |
188 | </tr></table> | |
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