BitMagic-C++
svsample06.cpp

Search/scan for elements in unordered, non-unique sparse vector

See also
bm::sparse_vector<>::const_iterator
bm::sparse_vector<>::back_insert_iterator
bm::sparse_vector_scanner
/*
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 svsample06.cpp
Search/scan for elements in unordered, non-unique sparse vector
\sa bm::sparse_vector<>::const_iterator
\sa bm::sparse_vector<>::back_insert_iterator
\sa bm::sparse_vector_scanner
*/
/*! \file svsample06.cpp
\brief Example: sparse_vector<> scan search (non-ordered set functionality)
*/
#include <iostream>
#include <vector>
#include <chrono>
#include <algorithm>
#include <random>
#include <stdexcept>
#include "bmsparsevec.h"
#include "bmtimer.h"
using namespace std;
// ----------------------------------------------------
// Global parameters and types
// ----------------------------------------------------
const unsigned value_max = 1250000; // range of variants of events [0..max]
const unsigned test_size = 250000000; // vector size to generate
// -------------------------------------------
// Random generator
// -------------------------------------------
std::random_device rand_dev;
std::mt19937 gen(rand_dev());
std::uniform_int_distribution<> rand_dis(1, value_max); // generate uniform numebrs for [1, vector_max]
// timing storage for benchmarking
// Function to generate test vector set with some NULL values stored as a
// separate bit-bector
//
static
void generate_test_set(std::vector<unsigned>& vect,
bm::bvector<>& bv_null,
{
// back insert iterator is faster than random element access for sparse vector
//
vect.resize(test_size);
bv_null.reset();
for (unsigned i = 0; i < test_size; ++i)
{
unsigned v = unsigned(rand_dis(gen));
vect[i] = v;
bv_null[i] = true; // not NULL(assigned) element
*bi = v; // push back an element to sparse vector
if (i % 64 == 0)
{
bi.add_null(5); // add 5 unassigned elements using back inserter
i += 5; // insert a small NULL plate (unassigned values)
}
} // for
}
// plain scan in std::vector<>, matching values are indexed
// in result bit-vector (subset projection)
// values are added, so multiple calls result in subset addition
static
void vector_search(const std::vector<unsigned>& vect,
const bm::bvector<>& bv_null,
unsigned value,
bm::bvector<>& bv_res)
{
bv_res.init(); // always use init() if set_bit_no_check()
for (size_t i = 0; i < vect.size(); ++i)
{
if (vect[i] == value)
} // for
bv_res &= bv_null; // correct results to only include non-NULL values
}
inline
{
cout << "( count = " << bv.count() << ")" << ": [";
for (; en.valid(); ++en)
cout << *en << ", ";
cout << "]" << endl;
}
int main(void)
{
try
{
// First, lets run, simple (printable) search case
//
{
sv.set(2, 25);
sv.set(3, 35);
sv.set(7, 75);
sv.set(1000, 2000);
sv.set(256, 2001);
sv.set(77, 25);
bm::bvector<> bv_found; // search results vector
scanner.find_eq(sv, 25, bv_found); // seach for all values == 25
print_bvector(bv_found); // print results
scanner.invert(sv, bv_found); // invert search results to NOT EQ
print_bvector(bv_found); // print all != 25
}
std::vector<unsigned> vect;
bm::bvector<> bv_null;
{
bm::chrono_taker tt1("0. test set generate ", 1, &timing_map);
generate_test_set(vect, bv_null, sv);
}
unsigned search_repeats = 500;
// generate a search vector for benchmarking
//
std::vector<unsigned> search_vect;
{
bm::bvector<> bv_tmp;
search_vect.reserve(search_repeats);
for (unsigned i = 0; i < search_repeats;)
{
if (!bv_tmp.test(idx)) // check if number is unique
{
search_vect.push_back(idx);
bv_tmp[idx] = 1;
++i;
}
}
}
// run benchmarks
//
bm::bvector<> bv_res1;
bm::bvector<> bv_res2;
bm::bvector<> bv_res3;
{
bm::chrono_taker tt1("1. std::vector<> scan ", search_repeats, &timing_map);
for (unsigned i = 0; i < search_repeats; ++i)
{
unsigned vs = search_vect[i];
vector_search(vect, bv_null, vs, bv_res1);
} // for
}
{
bm::chrono_taker tt1("2. sparse_vector<> scan ", search_repeats, &timing_map);
scanner.find_eq(sv, search_vect.begin(), search_vect.end(), bv_res2);
}
// check jus in case if results look correct
if (bv_res1.compare(bv_res2) != 0)
{
std::cerr << "2. Search result mismatch!" << std::endl;
}
{
bv_res3.init(); // always init before calling "set_bit_no_check()"
bm::chrono_taker tt1("3. sparse_vector<>::const_iterator search ", search_repeats, &timing_map);
// prepare a unique search set
bm::combine_or(bv_search, search_vect.begin(), search_vect.end());
for (; it != it_end; ++it)
{
unsigned v = *it;
if (bv_search.test(v))
{
bv_res3.set_bit_no_check(it.pos());
}
} // for
}
// paranoiya check
if (bv_res1.compare(bv_res3) != 0)
{
std::cerr << "3. Search result mismatch!" << std::endl;
}
}
catch(std::exception& ex)
{
std::cerr << ex.what() << std::endl;
return 1;
}
return 0;
}