BitMagic-C++
sample3.cpp
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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 sample3.cpp
20  Exmaple demonstrates using bitvectors with different initial
21  block allocation strategy.
22  Bitvector 1 (bv1) by default working without RLE compression option
23  (best performance, maximum memory consumption).
24  Bitvector 2 (bv2) will be working in compression mode and use less memory.
25 
26  \sa bm::bvector<>::set_new_blocks_strat()
27 
28  For more information please visit: http://bmagic.sourceforge.net
29 
30 */
31 /*! \file sample3.cpp
32  \brief Example: bvector<> with different allocation/compression strategies
33 */
34 #include <stdlib.h>
35 #include <iostream>
36 #include "bm.h"
37 
38 using namespace std;
39 
40 const unsigned MAX_VALUE = 1000000;
41 
42 // This procedure creates very dense bitvectors.
43 // The resulting set will consists mostly from ON (1) bits
44 // interrupted with small gaps of 0 bits.
45 static
47 {
48  for (unsigned i = 0; i < MAX_VALUE; ++i)
49  {
50  if (rand() % 2500)
51  {
52  bv1->set_bit(i);
53  bv2->set_bit(i);
54  }
55  }
56 }
57 
58 static
60 {
62  bv.calc_stat(&st);
63 
64  cout << "Bits count:" << bv.count() << endl;
65  cout << "Bit blocks:" << st.bit_blocks << endl;
66  cout << "GAP blocks:" << st.gap_blocks << endl;
67  cout << "Memory used:"<< st.memory_used << endl;
68  cout << "Max.serialize mem.:" << st.max_serialize_mem << endl << endl;;
69 }
70 
71 
72 int main(void)
73 {
74  try
75  {
76  bm::bvector<> bv1;
77  bm::bvector<> bv2;
78 
79  bv2.set_new_blocks_strat(bm::BM_GAP); // set DGAP compression mode ON
80 
81  fill_bvector(&bv1, &bv2); // Fill both bvectors with the same values
82 
83  // For a given distrubution statistics should demonstrate
84  // lower memory consumption for the vector with compression
85 
86  print_statistics(bv1);
87  print_statistics(bv2);
88 
89  // Now run optimization procedure for bv1 and see statistics.
90  bv1.optimize();
91 
92  print_statistics(bv1);
93  }
94  catch(std::exception& ex)
95  {
96  std::cerr << ex.what() << std::endl;
97  }
98 
99  return 0;
100 }
101 
bm::bvector::calc_stat
void calc_stat(struct bm::bvector< Alloc >::statistics *st) const BMNOEXCEPT
Calculates bitvector statistics.
Definition: bm.h:3419
bm::bv_statistics::max_serialize_mem
size_t max_serialize_mem
estimated maximum memory for serialization
Definition: bmfunc.h:60
bm::bvector::set_new_blocks_strat
void set_new_blocks_strat(strategy strat)
Sets new blocks allocation strategy.
Definition: bm.h:1836
MAX_VALUE
const unsigned MAX_VALUE
Definition: sample3.cpp:40
bm::bv_statistics::bit_blocks
size_t bit_blocks
Number of bit blocks.
Definition: bmfunc.h:56
bm::bv_statistics::gap_blocks
size_t gap_blocks
Number of GAP blocks.
Definition: bmfunc.h:57
fill_bvector
static void fill_bvector(bm::bvector<> *bv1, bm::bvector<> *bv2)
Definition: sample3.cpp:46
bm::bvector<>
bm::bvector::count
size_type count() const BMNOEXCEPT
population cout (count of ON bits)
Definition: bm.h:2220
print_statistics
static void print_statistics(const bm::bvector<> &bv)
Definition: sample3.cpp:59
bm::BM_GAP
@ BM_GAP
GAP compression is ON.
Definition: bmconst.h:144
main
int main(void)
Definition: sample3.cpp:72
bm::bv_statistics::memory_used
size_t memory_used
memory usage for all blocks and service tables
Definition: bmfunc.h:61
bm.h
Compressed bit-vector bvector<> container, set algebraic methods, traversal iterators.
bm::bvector::set_bit
bool set_bit(size_type n, bool val=true)
Sets bit n.
Definition: bm.h:3643
bm::bvector::optimize
void optimize(bm::word_t *temp_block=0, optmode opt_mode=opt_compress, statistics *stat=0)
Optimize memory bitvector's memory allocation.
Definition: bm.h:3097
bm::bvector::statistics
Statistical information about bitset's memory allocation details.
Definition: bm.h:121