BitMagic-C++
sample16.cpp

Example for finding first and last bits in bit-vector (dynamic range).Ranges of bit-vectors can be used to find probability of intersection. For instance, in some corner cases AND product can be predicted empty if vectors belong to different ranges.

@sa bm::aggregator
/*
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 sample16.cpp
Example for finding first and last bits in bit-vector (dynamic range).
Ranges of bit-vectors can be used to find probability of intersection.
For instance, in some corner cases AND product can be predicted empty if vectors
belong to different ranges.
@sa bm::aggregator
*/
/*! \file sample16.cpp
\brief Example: how to use bm::aggregator<> for logical operations
bm::aggregator<> uses cache blocking techniques and bandwidth optimizations
to do logical operations (OR, AND, AND-SUB) faster, than if we do it by
combining bit-vectors one by one, sequentially.
*/
#include <stdlib.h>
#include <iostream>
#include <vector>
#include <memory>
#include "bm.h"
#include "bmaggregator.h"
// Utility template function used to print container
template<class T> void PrintContainer(T first, T last)
{
if (first == last)
std::cout << "<EMPTY SET>";
else
for (; first != last; ++first)
std::cout << *first << ";";
std::cout << std::endl;
}
const unsigned max_vectors = 10;
int main(void)
{
try
{
// declare standalone aggregator for logical operations
// current version of aggregator is capped at 256 processing limit
{
std::cerr << "Too many bit-vectors!" << std::endl;
return 1;
}
std::cout << "AGRUMENT (GROUP 0) SETS:" << std::endl;
// make vector of bit-vectors, set some bits
std::vector<std::unique_ptr<bm::bvector<> > > vect;
for (unsigned i = 0; i < max_vectors; ++i)
{
std::unique_ptr<bm::bvector<>> bv(new bm::bvector<>());
bv->set(i);
bv->set(i+1);
bv->set(10000);
bv->set(20000);
PrintContainer(bv->first(), bv->end());
bv->optimize();
vect.push_back(std::move(bv));
}
std::cout << std::endl;
try
{
// in a loop we add all agruments to the aggregator
// (aggregator does not take ownership of pointers it receives)
//
for (unsigned i = 0; i < vect.size(); ++i)
{
agg.add(vect[i].get());
}
bm::bvector<> bv_res; // target vector for aggregation
agg.combine_or(bv_res); // perform logical OR on a vector group
std::cout << "OR:" << std::endl;
PrintContainer(bv_res.first(), bv_res.end()); // 0, 1, 2, 3, 4... 10000, 20000
// since we did not call bm::aggregator::reset() the vector group
// still remains attached
std::cout << "AND:" << std::endl;
agg.combine_and(bv_res); // AND on the same vector group
PrintContainer(bv_res.first(), bv_res.end()); // 10000, 20000
agg.reset(); // reset the aggregator
// fused logical AND MINUS example
// AND(vector-group-0) SUBstract (AND NOT) vector-group-1
for (unsigned i = 0; i < vect.size(); ++i)
{
const unsigned group0 = 0; // vector group 0
agg.add(vect[i].get(), group0);
}
// Note that we do not set vector group 1 yet, so operation just
// runs as a regular AND MINUS an empty-set
agg.combine_and_sub(bv_res); // AND-SUB vector group1 and group2
std::cout << "AND-SUB(empty):" << std::endl;
PrintContainer(bv_res.first(), bv_res.end()); // 10000, 20000
bm::bvector<> bv_not { 10, 10000 };
agg.add(&bv_not, 1); // add to vector-group-1
agg.combine_and_sub(bv_res); // AND-SUB vector group0 minus group1
std::cout << "AND-SUB:" << std::endl;
PrintContainer(bv_res.first(), bv_res.end()); // 20000
agg.reset();
}
catch(std::exception& ex)
{
agg.reset(); // reset
throw;
}
}
catch(std::exception& ex)
{
std::cerr << ex.what() << std::endl;
return 1;
}
return 0;
}