1 // Boost.Bimap
2 //
3 // Copyright (c) 2006-2007 Matias Capeletto
4 //
5 // Distributed under the Boost Software License, Version 1.0.
6 // (See accompanying file LICENSE_1_0.txt or copy at
7 // http://www.boost.org/LICENSE_1_0.txt)
8
9
10 // Boost.Bimap Example
11 //-----------------------------------------------------------------------------
12 // Hashed indices can be used as an alternative to ordered indices when fast
13 // lookup is needed and sorting information is of no interest. The example
14 // features a word counter where duplicate entries are checked by means of a
15 // hashed index.
16
17 #include <boost/config.hpp>
18
19 //[ code_mi_to_b_path_hashed_indices
20
21 #include <iostream>
22 #include <iomanip>
23
24 #include <boost/tokenizer.hpp>
25
26 #include <boost/bimap/bimap.hpp>
27 #include <boost/bimap/unordered_set_of.hpp>
28 #include <boost/bimap/multiset_of.hpp>
29 #include <boost/bimap/support/lambda.hpp>
30
31 using namespace boost::bimaps;
32
33 struct word {};
34 struct occurrences {};
35
36 typedef bimap
37 <
38
39 multiset_of< tagged<unsigned int,occurrences>, std::greater<unsigned int> >,
40 unordered_set_of< tagged< std::string, word> >
41
42 > word_counter;
43
44 typedef boost::tokenizer<boost::char_separator<char> > text_tokenizer;
45
main()46 int main()
47 {
48
49 std::string text=
50 "Relations between data in the STL are represented with maps."
51 "A map is a directed relation, by using it you are representing "
52 "a mapping. In this directed relation, the first type is related to "
53 "the second type but it is not true that the inverse relationship "
54 "holds. This is useful in a lot of situations, but there are some "
55 "relationships that are bidirectional by nature.";
56
57 // feed the text into the container
58
59 word_counter wc;
60 text_tokenizer tok(text,boost::char_separator<char>(" \t\n.,;:!?'\"-"));
61 unsigned int total_occurrences = 0;
62
63 for( text_tokenizer::const_iterator it = tok.begin(), it_end = tok.end();
64 it != it_end ; ++it )
65 {
66 ++total_occurrences;
67
68 word_counter::map_by<occurrences>::iterator wit =
69 wc.by<occurrences>().insert(
70 word_counter::map_by<occurrences>::value_type(0,*it)
71 ).first;
72
73 wc.by<occurrences>().modify_key( wit, ++_key);
74 }
75
76 // list words by frequency of appearance
77
78 std::cout << std::fixed << std::setprecision(2);
79
80 for( word_counter::map_by<occurrences>::const_iterator
81 wit = wc.by<occurrences>().begin(),
82 wit_end = wc.by<occurrences>().end();
83
84 wit != wit_end; ++wit )
85 {
86 std::cout << std::setw(15) << wit->get<word>() << ": "
87 << std::setw(5)
88 << 100.0 * wit->get<occurrences>() / total_occurrences << "%"
89 << std::endl;
90 }
91
92 return 0;
93 }
94 //]
95