BitMagic-C++
sample3.cpp

Exmaple demonstrates using bitvectors with different initial block allocation strategy.Bitvector 1 (bv1) by default working without RLE compression option (best performance, maximum memory consumption). Bitvector 2 (bv2) will be working in compression mode and use less memory.

See also
bm::bvector<>::set_new_blocks_strat()

For more information please visit: http://bmagic.sourceforge.net

/*
Copyright(c) 2002-2017 Anatoliy Kuznetsov(anatoliy_kuznetsov at yahoo.com)
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
For more information please visit: http://bitmagic.io
*/
/** \example sample3.cpp
Exmaple demonstrates using bitvectors with different initial
block allocation strategy.
Bitvector 1 (bv1) by default working without RLE compression option
(best performance, maximum memory consumption).
Bitvector 2 (bv2) will be working in compression mode and use less memory.
\sa bm::bvector<>::set_new_blocks_strat()
For more information please visit: http://bmagic.sourceforge.net
*/
/*! \file sample3.cpp
\brief Example: bvector<> with different allocation/compression strategies
*/
#include <stdlib.h>
#include <iostream>
#include "bm.h"
using namespace std;
const unsigned MAX_VALUE = 1000000;
// This procedure creates very dense bitvectors.
// The resulting set will consists mostly from ON (1) bits
// interrupted with small gaps of 0 bits.
static
{
for (unsigned i = 0; i < MAX_VALUE; ++i)
{
if (rand() % 2500)
{
bv1->set_bit(i);
bv2->set_bit(i);
}
}
}
static
{
bv.calc_stat(&st);
cout << "Bits count:" << bv.count() << endl;
cout << "Bit blocks:" << st.bit_blocks << endl;
cout << "GAP blocks:" << st.gap_blocks << endl;
cout << "Memory used:"<< st.memory_used << endl;
cout << "Max.serialize mem.:" << st.max_serialize_mem << endl << endl;;
}
int main(void)
{
try
{
bv2.set_new_blocks_strat(bm::BM_GAP); // set DGAP compression mode ON
fill_bvector(&bv1, &bv2); // Fill both bvectors with the same values
// For a given distrubution statistics should demonstrate
// lower memory consumption for the vector with compression
// Now run optimization procedure for bv1 and see statistics.
bv1.optimize();
}
catch(std::exception& ex)
{
std::cerr << ex.what() << std::endl;
}
return 0;
}
bm::bvector::calc_stat
void calc_stat(struct bm::bvector< Alloc >::statistics *st) const BMNOEXCEPT
Calculates bitvector statistics.
Definition: bm.h:3407
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:1824
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:2208
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:3631
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:3085
bm::bvector::statistics
Statistical information about bitset's memory allocation details.
Definition: bm.h:121