svsample04.cpp

Example how to use NULL-enabled sparse vector.

Example how to use NULL-enabled sparse vector

See also
  bm::sparse_vector
  bm::sparse_vector::clear
  bm::sparse_vector::set_null
  bm::sparse_vector::push_back
  bm::sparse_vector::decode
  bm::sparse_vector::resize
  bm::sparse_vector::join
  bm::bvector::enumerator

/*
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 svsample04.cpp
Example how to use NULL-enabled sparse vector
\sa bm::sparse_vector
\sa bm::sparse_vector::clear
\sa bm::sparse_vector::set_null
\sa bm::sparse_vector::push_back
\sa bm::sparse_vector::decode
\sa bm::sparse_vector::resize
\sa bm::sparse_vector::join
\sa bm::bvector::enumerator
*/
/*! \file svsample04.cpp
\brief Example: sparse_vector<> with NULL (unset) values
*/
#include <iostream>
#include <vector>
#include "bm.h"
#include "bmsparsevec.h"
#include "bmundef.h" /* clear the pre-proc defines from BM */
using namespace std;
static
void print_svector(const bm::sparse_vector<unsigned, bm::bvector<> >& sv)
{
if (sv.size() == 0)
{
cout << sv.size() << ": [ EMPTY ]" << endl;
return;
}
cout << sv.size() << ": [ ";
for (unsigned i = 0; i < sv.size(); ++i)
{
unsigned v = sv.at(i);
bool is_null = sv.is_null(i);
if (is_null)
cout << "NULL";
else
cout << v << "";
if (i == sv.size()-1)
cout << " ]";
else
cout << ", ";
}
cout << endl;
}
int main(void)
{
try
{
// sparse vector can support unassigned value semantics
// (also known as NULL value in databases)
//
// to enable this function sparse_vector<> needs to be constructed using
// special flag ( bm::use_null )
//
bm::sparse_vector<unsigned, bm::bvector<> > sv1(bm::use_null);
sv1.resize(10);
sv1.set(2, 25);
sv1.set(3, 35);
sv1.set(7, 75);
print_svector(sv1); // 10: [ NULL, NULL, 25, 35, NULL, NULL, NULL, 75, NULL, NULL ]
sv1.set_null(7);
print_svector(sv1); // 10: [ NULL, NULL, 25, 35, NULL, NULL, NULL, NULL, NULL, NULL ]
unsigned arr[3] = {1,2,3};
sv1.import(arr, 3, 9); // import from a C-style array (by index 9)
print_svector(sv1); // 12: [ NULL, NULL, 25, 35, NULL, NULL, NULL, NULL, NULL, 1, 2, 3 ]
sv1.clear(2, true); // clear element and set to NULL
print_svector(sv1); // 12: [ NULL, NULL, NULL, 35, NULL, NULL, NULL, NULL, NULL, 1, 2, 3 ]
sv1.clear(2, false); // clear element (not NULL anymore)
print_svector(sv1); // 12: [ NULL, NULL, 0, 35, NULL, NULL, NULL, NULL, NULL, 1, 2, 3 ]
sv1.clear(3, false); // clear element (it stays NOT NULL)
print_svector(sv1); // 12: [ NULL, NULL, NULL, 0, NULL, NULL, NULL, NULL, NULL, 1, 2, 3 ]
sv1.clear();
print_svector(sv1); // 0: [ EMPTY ]
sv1.resize(3);
print_svector(sv1); // 3: [ NULL, NULL, NULL ]
sv1.push_back(10);
sv1.push_back(20);
sv1.push_back(30);
print_svector(sv1); // 5: [ NULL, NULL, NULL, 10, 20, 30 ]
// bulk clear the vector (can be a lot faster than random element access)
{
bm::bvector<> bv_clear { 3, 5 }; // clear sv1[3]=0 and sv1[5]=0
sv1.clear(bv_clear); // clear multiple elemets at once
print_svector(sv1); // 5: [ NULL, NULL, NULL, 0, 20, 0 ]
// please note, that clear does not set elements to NULL (but to 0)
}
sv1.set(1, 10);
sv1.set(2, 20);
sv1.push_back(40);
print_svector(sv1); // 5: [ NULL, 10, 20, 0, 20, 0, 40 ]
// bulk set_null the vector
{
bm::bvector<> bv_set_null { 0, 1, 3, 5 }; // NULLs sv1[3] and sv1[5]
sv1.set_null(bv_set_null); // clear multiple elemets at once
print_svector(sv1); // 5: [ NULL, NULL, 20, NULL, 20, NULL, 40]
// please note, that clear both sets to zero and sets it to NULL
}
// construct not-null-able sparse vector
//
bm::sparse_vector<unsigned, bm::bvector<> > sv2;
sv2.push_back(100);
sv2.push_back(200);
sv1.join(sv2); // merge two vectors together
print_svector(sv1); // 5: [ 100, 200, NULL, 10, 20 ]
// construct another NULL-able vector for another join
bm::sparse_vector<unsigned, bm::bvector<> > sv3(bm::use_null);
sv3.resize(9);
sv3.push_back(300);
// this join will fully respect the NULL flags assigned in both sparse vectors
sv1.join(sv3);
print_svector(sv1); // 10: [ 100, 200, NULL, 10, 20, NULL, NULL, NULL, NULL, 300 ]
// traverse and print the non-NULL values
// using bit-vector of assigned values
//
// [0] = 100, [1] = 200, [3] = 10, [4] = 20, [9] = 300
//
{
const bm::bvector<>* bv_non_null = sv1.get_null_bvector();
if (bv_non_null)
{
bm::bvector<>::enumerator en = bv_non_null->first();
for (; en.valid(); ++en)
{
unsigned idx = *en;
unsigned v = sv1[idx];
std::cout << "[" << idx << "] = " << v << ", ";
}
std::cout << endl;
}
}
// decode sparse_vector with NULL values
// decode ignores NULLs (in our case replaces values with '0s'
//
{
std::vector<unsigned> v1(sv1.size());
sv1.decode(&v1[0], 0, sv1.size()); // extract elements starting from 0
// 100,200,0,10,20,0,0,0,0,300,
for (unsigned i = 0; i < v1.size(); ++i)
{
cout << v1[i] << ",";
}
cout << endl;
}
}
catch(std::exception& ex)
{
std::cerr << ex.what() << std::endl;
return 1;
}
return 0;
}
bm.h
Compressed bit-vector bvector<> container, set algebraic methods, traversal iterators.
bmsparsevec.h
Sparse constainer sparse_vector<> for integer types using bit-transposition transform.
bmundef.h
pre-processor un-defines to avoid global space pollution (internal)
bm::bvector::enumerator
Constant iterator designed to enumerate "ON" bits.
Definition bm.h:603
bm::bvector::iterator_base::valid
bool valid() const BMNOEXCEPT
Checks if iterator is still valid.
Definition bm.h:283
bm::bvector
Bitvector Bit-vector container with runtime compression of bits.
Definition bm.h:115
bm::bvector::first
enumerator first() const
Returns enumerator pointing on the first non-zero bit.
Definition bm.h:1871
bm::bvector::clear
void clear(const size_type *ids, size_type ids_size, bm::sort_order so=bm::BM_UNKNOWN)
clear list of bits in this bitset
Definition bm.h:4149
bm::sparse_vector
succinct sparse vector with runtime compression using bit-slicing / transposition method
Definition bmsparsevec.h:87
bm::sparse_vector::push_back
void push_back(value_type v)
push value back into vector
Definition bmsparsevec.h:1883
bm::use_null
@ use_null
support "non-assigned" or "NULL" logic
Definition bmconst.h:230
main
int main(void)
Definition sample1.cpp:43
print_svector
static void print_svector(const bm::sparse_vector< unsigned, bm::bvector<> > &sv)
Definition svsample04.cpp:47