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25 <div class=
"section boost_icl_examples_partys_height_average" lang=
"en">
26 <div class=
"titlepage"><div><div><h3 class=
"title">
27 <a name=
"boost_icl.examples.partys_height_average"></a><a class=
"link" href=
"partys_height_average.html" title=
"Party's height average"> Party's height
29 </h3></div></div></div>
31 In the example
<code class=
"computeroutput"><span class=
"identifier">partys_height_average
</span><span class=
"special">.
</span><span class=
"identifier">cpp
</span></code> we
32 compute yet another aggregation: The average height of guests. This is done
33 by defining a
<code class=
"computeroutput"><span class=
"keyword">class
</span> <span class=
"identifier">counted_sum
</span></code>
34 that sums up heights and counts the number of guests via an
<code class=
"computeroutput"><span class=
"keyword">operator
</span> <span class=
"special">+=
</span></code>.
37 Based on the
<code class=
"computeroutput"><span class=
"keyword">operator
</span> <span class=
"special">+=
</span></code>
38 we can aggregate counted sums on addition of interval value pairs into an
46 <pre class=
"programlisting"><span class=
"comment">// The next line includes
<boost/date_time/posix_time/posix_time.hpp
>
47 </span><span class=
"comment">// and a few lines of adapter code.
48 </span><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">ptime
</span><span class=
"special">.
</span><span class=
"identifier">hpp
</span><span class=
"special">></span>
49 <span class=
"preprocessor">#include
</span> <span class=
"special"><</span><span class=
"identifier">iostream
</span><span class=
"special">></span>
50 <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">interval_map
</span><span class=
"special">.
</span><span class=
"identifier">hpp
</span><span class=
"special">></span>
51 <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>
53 <span class=
"keyword">using
</span> <span class=
"keyword">namespace
</span> <span class=
"identifier">std
</span><span class=
"special">;
</span>
54 <span class=
"keyword">using
</span> <span class=
"keyword">namespace
</span> <span class=
"identifier">boost
</span><span class=
"special">::
</span><span class=
"identifier">posix_time
</span><span class=
"special">;
</span>
55 <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>
58 <span class=
"keyword">class
</span> <span class=
"identifier">counted_sum
</span>
59 <span class=
"special">{
</span>
60 <span class=
"keyword">public
</span><span class=
"special">:
</span>
61 <span class=
"identifier">counted_sum
</span><span class=
"special">():
</span><span class=
"identifier">_sum
</span><span class=
"special">(
</span><span class=
"number">0</span><span class=
"special">),
</span><span class=
"identifier">_count
</span><span class=
"special">(
</span><span class=
"number">0</span><span class=
"special">){}
</span>
62 <span class=
"identifier">counted_sum
</span><span class=
"special">(
</span><span class=
"keyword">int
</span> <span class=
"identifier">sum
</span><span class=
"special">):
</span><span class=
"identifier">_sum
</span><span class=
"special">(
</span><span class=
"identifier">sum
</span><span class=
"special">),
</span><span class=
"identifier">_count
</span><span class=
"special">(
</span><span class=
"number">1</span><span class=
"special">){}
</span>
64 <span class=
"keyword">int
</span> <span class=
"identifier">sum
</span><span class=
"special">()
</span><span class=
"keyword">const
</span> <span class=
"special">{
</span><span class=
"keyword">return
</span> <span class=
"identifier">_sum
</span><span class=
"special">;}
</span>
65 <span class=
"keyword">int
</span> <span class=
"identifier">count
</span><span class=
"special">()
</span><span class=
"keyword">const
</span><span class=
"special">{
</span><span class=
"keyword">return
</span> <span class=
"identifier">_count
</span><span class=
"special">;}
</span>
66 <span class=
"keyword">double
</span> <span class=
"identifier">average
</span><span class=
"special">()
</span><span class=
"keyword">const
</span><span class=
"special">{
</span> <span class=
"keyword">return
</span> <span class=
"identifier">_count
</span><span class=
"special">==
</span><span class=
"number">0</span> <span class=
"special">?
</span> <span class=
"number">0.0</span> <span class=
"special">:
</span> <span class=
"identifier">_sum
</span><span class=
"special">/
</span><span class=
"keyword">static_cast
</span><span class=
"special"><</span><span class=
"keyword">double
</span><span class=
"special">>(
</span><span class=
"identifier">_count
</span><span class=
"special">);
</span> <span class=
"special">}
</span>
68 <span class=
"identifier">counted_sum
</span><span class=
"special">&</span> <span class=
"keyword">operator
</span> <span class=
"special">+=
</span> <span class=
"special">(
</span><span class=
"keyword">const
</span> <span class=
"identifier">counted_sum
</span><span class=
"special">&</span> <span class=
"identifier">right
</span><span class=
"special">)
</span>
69 <span class=
"special">{
</span> <span class=
"identifier">_sum
</span> <span class=
"special">+=
</span> <span class=
"identifier">right
</span><span class=
"special">.
</span><span class=
"identifier">sum
</span><span class=
"special">();
</span> <span class=
"identifier">_count
</span> <span class=
"special">+=
</span> <span class=
"identifier">right
</span><span class=
"special">.
</span><span class=
"identifier">count
</span><span class=
"special">();
</span> <span class=
"keyword">return
</span> <span class=
"special">*
</span><span class=
"keyword">this
</span><span class=
"special">;
</span> <span class=
"special">}
</span>
71 <span class=
"keyword">private
</span><span class=
"special">:
</span>
72 <span class=
"keyword">int
</span> <span class=
"identifier">_sum
</span><span class=
"special">;
</span>
73 <span class=
"keyword">int
</span> <span class=
"identifier">_count
</span><span class=
"special">;
</span>
74 <span class=
"special">};
</span>
76 <span class=
"keyword">bool
</span> <span class=
"keyword">operator
</span> <span class=
"special">==
</span> <span class=
"special">(
</span><span class=
"keyword">const
</span> <span class=
"identifier">counted_sum
</span><span class=
"special">&</span> <span class=
"identifier">left
</span><span class=
"special">,
</span> <span class=
"keyword">const
</span> <span class=
"identifier">counted_sum
</span><span class=
"special">&</span> <span class=
"identifier">right
</span><span class=
"special">)
</span>
77 <span class=
"special">{
</span> <span class=
"keyword">return
</span> <span class=
"identifier">left
</span><span class=
"special">.
</span><span class=
"identifier">sum
</span><span class=
"special">()==
</span><span class=
"identifier">right
</span><span class=
"special">.
</span><span class=
"identifier">sum
</span><span class=
"special">()
</span> <span class=
"special">&&</span> <span class=
"identifier">left
</span><span class=
"special">.
</span><span class=
"identifier">count
</span><span class=
"special">()==
</span><span class=
"identifier">right
</span><span class=
"special">.
</span><span class=
"identifier">count
</span><span class=
"special">();
</span> <span class=
"special">}
</span>
80 <span class=
"keyword">void
</span> <span class=
"identifier">partys_height_average
</span><span class=
"special">()
</span>
81 <span class=
"special">{
</span>
82 <span class=
"identifier">interval_map
</span><span class=
"special"><</span><span class=
"identifier">ptime
</span><span class=
"special">,
</span> <span class=
"identifier">counted_sum
</span><span class=
"special">></span> <span class=
"identifier">height_sums
</span><span class=
"special">;
</span>
84 <span class=
"identifier">height_sums
</span> <span class=
"special">+=
</span>
85 <span class=
"identifier">make_pair
</span><span class=
"special">(
</span>
86 <span class=
"identifier">discrete_interval
</span><span class=
"special"><</span><span class=
"identifier">ptime
</span><span class=
"special">>::
</span><span class=
"identifier">right_open
</span><span class=
"special">(
</span>
87 <span class=
"identifier">time_from_string
</span><span class=
"special">(
</span><span class=
"string">"2008-05-20 19:30"</span><span class=
"special">),
</span>
88 <span class=
"identifier">time_from_string
</span><span class=
"special">(
</span><span class=
"string">"2008-05-20 23:00"</span><span class=
"special">)),
</span>
89 <span class=
"identifier">counted_sum
</span><span class=
"special">(
</span><span class=
"number">165</span><span class=
"special">));
</span> <span class=
"comment">// Mary is
1,
65 m tall.
91 <span class=
"identifier">height_sums
</span> <span class=
"special">+=
</span>
92 <span class=
"identifier">make_pair
</span><span class=
"special">(
</span>
93 <span class=
"identifier">discrete_interval
</span><span class=
"special"><</span><span class=
"identifier">ptime
</span><span class=
"special">>::
</span><span class=
"identifier">right_open
</span><span class=
"special">(
</span>
94 <span class=
"identifier">time_from_string
</span><span class=
"special">(
</span><span class=
"string">"2008-05-20 19:30"</span><span class=
"special">),
</span>
95 <span class=
"identifier">time_from_string
</span><span class=
"special">(
</span><span class=
"string">"2008-05-20 23:00"</span><span class=
"special">)),
</span>
96 <span class=
"identifier">counted_sum
</span><span class=
"special">(
</span><span class=
"number">180</span><span class=
"special">));
</span> <span class=
"comment">// Harry is
1,
80 m tall.
98 <span class=
"identifier">height_sums
</span> <span class=
"special">+=
</span>
99 <span class=
"identifier">make_pair
</span><span class=
"special">(
</span>
100 <span class=
"identifier">discrete_interval
</span><span class=
"special"><</span><span class=
"identifier">ptime
</span><span class=
"special">>::
</span><span class=
"identifier">right_open
</span><span class=
"special">(
</span>
101 <span class=
"identifier">time_from_string
</span><span class=
"special">(
</span><span class=
"string">"2008-05-20 20:10"</span><span class=
"special">),
</span>
102 <span class=
"identifier">time_from_string
</span><span class=
"special">(
</span><span class=
"string">"2008-05-21 00:00"</span><span class=
"special">)),
</span>
103 <span class=
"identifier">counted_sum
</span><span class=
"special">(
</span><span class=
"number">170</span><span class=
"special">));
</span> <span class=
"comment">// Diana is
1,
70 m tall.
105 <span class=
"identifier">height_sums
</span> <span class=
"special">+=
</span>
106 <span class=
"identifier">make_pair
</span><span class=
"special">(
</span>
107 <span class=
"identifier">discrete_interval
</span><span class=
"special"><</span><span class=
"identifier">ptime
</span><span class=
"special">>::
</span><span class=
"identifier">right_open
</span><span class=
"special">(
</span>
108 <span class=
"identifier">time_from_string
</span><span class=
"special">(
</span><span class=
"string">"2008-05-20 20:10"</span><span class=
"special">),
</span>
109 <span class=
"identifier">time_from_string
</span><span class=
"special">(
</span><span class=
"string">"2008-05-21 00:00"</span><span class=
"special">)),
</span>
110 <span class=
"identifier">counted_sum
</span><span class=
"special">(
</span><span class=
"number">165</span><span class=
"special">));
</span> <span class=
"comment">// Susan is
1,
65 m tall.
112 <span class=
"identifier">height_sums
</span> <span class=
"special">+=
</span>
113 <span class=
"identifier">make_pair
</span><span class=
"special">(
</span>
114 <span class=
"identifier">discrete_interval
</span><span class=
"special"><</span><span class=
"identifier">ptime
</span><span class=
"special">>::
</span><span class=
"identifier">right_open
</span><span class=
"special">(
</span>
115 <span class=
"identifier">time_from_string
</span><span class=
"special">(
</span><span class=
"string">"2008-05-20 22:15"</span><span class=
"special">),
</span>
116 <span class=
"identifier">time_from_string
</span><span class=
"special">(
</span><span class=
"string">"2008-05-21 00:30"</span><span class=
"special">)),
</span>
117 <span class=
"identifier">counted_sum
</span><span class=
"special">(
</span><span class=
"number">200</span><span class=
"special">));
</span> <span class=
"comment">// Peters height is
2,
00 m
119 <span class=
"identifier">interval_map
</span><span class=
"special"><</span><span class=
"identifier">ptime
</span><span class=
"special">,
</span> <span class=
"identifier">counted_sum
</span><span class=
"special">>::
</span><span class=
"identifier">iterator
</span> <span class=
"identifier">height_sum_
</span> <span class=
"special">=
</span> <span class=
"identifier">height_sums
</span><span class=
"special">.
</span><span class=
"identifier">begin
</span><span class=
"special">();
</span>
120 <span class=
"identifier">cout
</span> <span class=
"special"><<</span> <span class=
"string">"-------------- History of average guest height -------------------\n"</span><span class=
"special">;
</span>
121 <span class=
"keyword">while
</span><span class=
"special">(
</span><span class=
"identifier">height_sum_
</span> <span class=
"special">!=
</span> <span class=
"identifier">height_sums
</span><span class=
"special">.
</span><span class=
"identifier">end
</span><span class=
"special">())
</span>
122 <span class=
"special">{
</span>
123 <span class=
"identifier">discrete_interval
</span><span class=
"special"><</span><span class=
"identifier">ptime
</span><span class=
"special">></span> <span class=
"identifier">when
</span> <span class=
"special">=
</span> <span class=
"identifier">height_sum_
</span><span class=
"special">-
></span><span class=
"identifier">first
</span><span class=
"special">;
</span>
125 <span class=
"keyword">double
</span> <span class=
"identifier">height_average
</span> <span class=
"special">=
</span> <span class=
"special">(*
</span><span class=
"identifier">height_sum_
</span><span class=
"special">++).
</span><span class=
"identifier">second
</span><span class=
"special">.
</span><span class=
"identifier">average
</span><span class=
"special">();
</span>
126 <span class=
"identifier">cout
</span> <span class=
"special"><<</span> <span class=
"identifier">setprecision
</span><span class=
"special">(
</span><span class=
"number">3</span><span class=
"special">)
</span>
127 <span class=
"special"><<</span> <span class=
"string">"["</span> <span class=
"special"><<</span> <span class=
"identifier">first
</span><span class=
"special">(
</span><span class=
"identifier">when
</span><span class=
"special">)
</span> <span class=
"special"><<</span> <span class=
"string">" - "</span> <span class=
"special"><<</span> <span class=
"identifier">upper
</span><span class=
"special">(
</span><span class=
"identifier">when
</span><span class=
"special">)
</span> <span class=
"special"><<</span> <span class=
"string">")"</span>
128 <span class=
"special"><<</span> <span class=
"string">": "</span> <span class=
"special"><<</span> <span class=
"identifier">height_average
</span> <span class=
"special"><<</span><span class=
"string">" cm = "</span> <span class=
"special"><<</span> <span class=
"identifier">height_average
</span><span class=
"special">/
</span><span class=
"number">30.48</span> <span class=
"special"><<</span> <span class=
"string">" ft"</span> <span class=
"special"><<</span> <span class=
"identifier">endl
</span><span class=
"special">;
</span>
129 <span class=
"special">}
</span>
130 <span class=
"special">}
</span>
133 <span class=
"keyword">int
</span> <span class=
"identifier">main
</span><span class=
"special">()
</span>
134 <span class=
"special">{
</span>
135 <span class=
"identifier">cout
</span> <span class=
"special"><<</span> <span class=
"string">">>Interval Container Library: Sample partys_height_average.cpp <<\n"</span><span class=
"special">;
</span>
136 <span class=
"identifier">cout
</span> <span class=
"special"><<</span> <span class=
"string">"------------------------------------------------------------------\n"</span><span class=
"special">;
</span>
137 <span class=
"identifier">partys_height_average
</span><span class=
"special">();
</span>
138 <span class=
"keyword">return
</span> <span class=
"number">0</span><span class=
"special">;
</span>
139 <span class=
"special">}
</span>
141 <span class=
"comment">// Program output:
142 </span><span class=
"comment">/*-----------------------------------------------------------------------------
143 >>Interval Container Library: Sample partys_height_average.cpp
<<
144 ------------------------------------------------------------------
145 -------------- History of average guest height -------------------
146 [
2008-May-
20 19:
30:
00 -
2008-May-
20 20:
10:
00):
173 cm =
5.66 ft
147 [
2008-May-
20 20:
10:
00 -
2008-May-
20 22:
15:
00):
170 cm =
5.58 ft
148 [
2008-May-
20 22:
15:
00 -
2008-May-
20 23:
00:
00):
176 cm =
5.77 ft
149 [
2008-May-
20 23:
00:
00 -
2008-May-
21 00:
00:
00):
178 cm =
5.85 ft
150 [
2008-May-
21 00:
00:
00 -
2008-May-
21 00:
30:
00):
200 cm =
6.56 ft
151 -----------------------------------------------------------------------------*/
</span>
158 Required for
<code class=
"computeroutput"><span class=
"keyword">class
</span> <span class=
"identifier">counted_sum
</span></code>
159 is a default constructor
<code class=
"computeroutput"><span class=
"identifier">counted_sum
</span><span class=
"special">()
</span></code>and an
<code class=
"computeroutput"><span class=
"keyword">operator
</span>
160 <span class=
"special">==
</span></code> to test equality. To enable additive
161 aggregation on overlap also an
<code class=
"computeroutput"><span class=
"keyword">operator
</span>
162 <span class=
"special">+=
</span></code> is needed.
165 Note that no
<code class=
"computeroutput"><span class=
"keyword">operator
</span> <span class=
"special">-=
</span></code>
166 for a subtraction of
<code class=
"computeroutput"><span class=
"identifier">counted_sum
</span></code>
167 values is defined. So you can only add to the
<code class=
"computeroutput"><span class=
"identifier">interval_map
</span><span class=
"special"><</span><span class=
"identifier">ptime
</span><span class=
"special">,
</span> <span class=
"identifier">counted_sum
</span><span class=
"special">></span></code> but not subtract from it.
170 In many real world applications only addition is needed and user defined
171 classes will work fine, if they only implement
<code class=
"computeroutput"><span class=
"keyword">operator
</span>
172 <span class=
"special">+=
</span></code>. Only if any of the
<code class=
"computeroutput"><span class=
"keyword">operator
</span></code>s
<code class=
"computeroutput"><span class=
"special">-=
</span></code>
173 or
<code class=
"computeroutput"><span class=
"special">-
</span></code> is called on the interval_map,
174 the user defined class has to implement it's own
<code class=
"computeroutput"><span class=
"keyword">operator
</span>
175 <span class=
"special">-=
</span></code> to provide the subtractive aggregation
179 <table xmlns:
rev=
"http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width=
"100%"><tr>
180 <td align=
"left"></td>
181 <td align=
"right"><div class=
"copyright-footer">Copyright
© 2007 -
2010 Joachim Faulhaber
<br>Copyright
© 1999 -
2006 Cortex Software GmbH
<p>
182 Distributed under the Boost Software License, Version
1.0. (See accompanying
183 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>)
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