BitMagic-C++: svsample05.cpp Source File

BitMagic-C++

svsample05.cpp
Go to the documentation of this file.
1 /*
2 Copyright(c) 2002-2017 Anatoliy Kuznetsov(anatoliy_kuznetsov at yahoo.com)
3
4 Licensed under the Apache License, Version 2.0 (the "License");
5 you may not use this file except in compliance with the License.
6 You may obtain a copy of the License at
7
8 http://www.apache.org/licenses/LICENSE-2.0
9
10 Unless required by applicable law or agreed to in writing, software
11 distributed under the License is distributed on an "AS IS" BASIS,
12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 See the License for the specific language governing permissions and
14 limitations under the License.
15
16 For more information please visit: http://bitmagic.io
17 */
18
19 /** \example svsample05.cpp
20 Example how to use for bvector re-mapping / transformation
21 based on sparse_vector as a translation table.
22
23 Example discusses how use of NULL (unassigned) sparse_vector<> semantics affects
24 behavior of image transformation algorithm.
25
26 \sa bm::sparse_vector<>
27 \sa bm::set2set_11_transform
28 */
29
30 /*! \file svsample05.cpp
31 \brief Example: sparse_vector<> used for set 2 set remapping (theory of groups Image)
32 */
33
34
35 #include <iostream>
36 #include <vector>
37
38 #include "bm.h"
39 #include "bmsparsevec.h"
40 #include "bmsparsevec_algo.h"
41
42 using namespace std;
43
44 typedef bm::sparse_vector<bm::id_t, bm::bvector<> > sparse_vector_u32;
45
46 static
47 void print_svector(const sparse_vector_u32& sv)
48 {
49 if (sv.size() == 0)
50 {
51 cout << sv.size() << ": [ EMPTY ]" << endl;
52 return;
53 }
54 cout << sv.size() << ": [ ";
55 for (unsigned i = 0; i < sv.size(); ++i)
56 {
57 unsigned v = sv.at(i);
58 bool is_null = sv.is_null(i);
59
60 if (is_null)
61 cout << "NULL";
62 else
63 cout << v << "";
64
65 if (i == sv.size()-1)
66 cout << " ]";
67 else
68 cout << ", ";
69 }
70 cout << endl;
71 }
72
73 inline
74 void print_bvector(const bm::bvector<>& bv)
75 {
76 cout << "( count = " << bv.count() << ")" << ": [";
77 bm::bvector<>::enumerator en = bv.first();
78 for (; en.valid(); ++en)
79 {
80 cout << *en << ", ";
81 }
82 cout << "]" << endl;
83 }
84
85
86 int main(void)
87 {
88 try
89 {
90 // initialize sparse_vector as a binary relation (transform function)
91 // to translate from one set to another (please note it uses NULL values)
92 //
93 sparse_vector_u32 sv_transform(bm::use_null);
94
95 // transformation function defined as a table:
96 // 2 -> 25
97 // 3 -> 35
98 // 7 -> 75
99 // 1000 -> 2000
100 // 256 -> 2001
101
102 sv_transform.set(2, 25);
103 sv_transform.set(3, 35);
104 sv_transform.set(7, 75);
105 sv_transform.set(1000, 2000);
106 sv_transform.set(256, 2001);
107
108 print_svector(sv_transform);
109
110 // initialize input bit-vector
111 //
112 bm::bvector<> bv_in { 1, 2, 3, 1000, 256 };
113
114 bm::bvector<> bv_out;
115
116 bm::set2set_11_transform<sparse_vector_u32> func;
117 func.run(bv_in, sv_transform, bv_out);
118
119 std::cout << "re-mapped vector:" << endl;
120 print_bvector(bv_out); // ( count = 4): [25, 35, 2000, 2001, ]
121
122 // Please note, that remapping request for "1" cannot be satisfied
123 // as sv_transform vector did not assign this element so it has
124 // special unassigned, NULL value
125
126 bm::id_t from = 1;
127 bm::id_t to;
128 bool found = func.remap(1, sv_transform, to);
129 if (!found)
130 std::cout << from << " not mapped" << std::endl; // THIS works!
131 else
132 std::cout << from << " mapped to " << to << std::endl;
133
134
135 // now lets try another experiment here, construct image transform
136 // function as default NOT using NULL values
137
138 sparse_vector_u32 sv_transform2;
139
140 sv_transform2.set(2, 25);
141 sv_transform2.set(3, 35);
142 sv_transform2.set(7, 75);
143 sv_transform2.set(1000, 2000);
144 sv_transform2.set(256, 2001);
145
146 found = func.remap(1, sv_transform2, to);
147 if (!found)
148 std::cout << from << " not mapped" << std::endl;
149 else
150 std::cout << from << " mapped to " << to << std::endl; // Now THIS works!
151
152 // Please note that remapping for unassigned value - works and maps to 0
153 // because transformation sparse vector does not keep information about
154 // unassigned values, all unassigned are now implicitly assumed to be "0"
155
156 func.run(bv_in, sv_transform2, bv_out);
157
158 std::cout << "re-mapped vector2:" << endl;
159 print_bvector(bv_out); // ( count = 5): [0, 25, 35, 2000, 2001, ]
160
161 }
162 catch(std::exception& ex)
163 {
164 std::cerr << ex.what() << std::endl;
165 return 1;
166 }
167
168 return 0;
169 }
170
bm::set2set_11_transform::remap
void remap(const bvector_type &bv_in, bvector_type &bv_out)
Perform remapping (Image function) (based on attached translation table)
Definition: bmsparsevec_algo.h:982
bmsparsevec_algo.h
Algorithms for bm::sparse_vector.
bm::sparse_vector
sparse vector with runtime compression using bit transposition method
Definition: bmsparsevec.h:81
bm::set2set_11_transform
Integer set to set transformation (functional image in groups theory) https://en.wikipedia....
Definition: bmsparsevec_algo.h:773
bmsparsevec.h
Sparse constainer sparse_vector<> for integer types using bit-transposition transform.
bm::bvector::enumerator
Constant iterator designed to enumerate "ON" bits.
Definition: bm.h:599
bm::bvector<>
bm::use_null
@ use_null
support "non-assigned" or "NULL" logic
Definition: bmconst.h:215
print_svector
static void print_svector(const sparse_vector_u32 &sv)
Definition: svsample05.cpp:47
bm::bvector::count
size_type count() const BMNOEXCEPT
population cout (count of ON bits)
Definition: bm.h:2194
print_bvector
void print_bvector(const bm::bvector<> &bv)
Definition: svsample05.cpp:74
bm::bvector::iterator_base::valid
bool valid() const BMNOEXCEPT
Checks if iterator is still valid. Analog of != 0 comparison for pointers.
Definition: bm.h:280
bm::set2set_11_transform::run
void run(const bvector_type &bv_in, const SV &sv_brel, bvector_type &bv_out)
Run remap transformation.
Definition: bmsparsevec_algo.h:831
bm::sparse_vector::size
size_type size() const BMNOEXCEPT
return size of the vector
Definition: bmsparsevec.h:644
main
int main(void)
Definition: svsample05.cpp:86
bm::base_sparse_vector::is_null
bool is_null(size_type idx) const BMNOEXCEPT
test if specified element is NULL
Definition: bmbmatrix.h:1285
bm::id_t
unsigned int id_t
Definition: bmconst.h:37
sparse_vector_u32
bm::sparse_vector< bm::id_t, bm::bvector<> > sparse_vector_u32
Definition: svsample05.cpp:44
bm::sparse_vector::at
value_type at(size_type idx) const
access specified element with bounds checking
Definition: bmsparsevec.h:1434
bm::bvector::first
enumerator first() const
Returns enumerator pointing on the first non-zero bit.
Definition: bm.h:1770
bm.h
Compressed bit-vector bvector<> container, set algebraic methods, traversal iterators.
bm::sparse_vector::set
void set(size_type idx, value_type v)
set specified element with bounds checking and automatic resize
Definition: bmsparsevec.h:1469