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SignedRandomProjection.cpp
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SignedRandomProjection.cpp
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#include "SignedRandomProjection.h"
#include <iostream>
#include <algorithm>
#include <cmath>
using namespace std;
/* Author: Chen Luo and Anshumali Shrivastava
* COPYRIGHT PROTECTION
* Free for research use.
* For commercial use, contact: RICE UNIVERSITY INVENTION & PATENT or the Author.
*/
SignedRandomProjection::SignedRandomProjection(int dimention, int numOfHashes) {
_dim = dimention;
_numhashes = numOfHashes;
_samSize = ceil(_dim / 3);
int *a = new int[_dim];
for (size_t i = 0; i < _dim; i++) {
a[i] = i;
}
srand(time(0));
_randBits = new short *[_numhashes];
_indices = new int *[_numhashes];
for (size_t i = 0; i < _numhashes; i++) {
random_shuffle(&a[0], &a[_dim - 1]);
_randBits[i] = new short[_samSize];
_indices[i] = new int[_samSize];
for (size_t j = 0; j < _samSize; j++) {
_indices[i][j] = a[j];
int curr = rand();
if (curr % 2 == 0) {
_randBits[i][j] = 1;
} else {
_randBits[i][j] = -1;
}
}
}
}
int *SignedRandomProjection::getHash(double *vector, int length) {
// length should be = to _dim
int *hashes = new int[_numhashes];
#pragma omp parallel for
for (int i = 0; i < _numhashes; i++) {
double s = 0;
for (size_t j = 0; j < _samSize; j++) {
double v = vector[_indices[i][j]];
if (_randBits[i][j] >= 0) {
s += v;
} else {
s -= v;
}
}
hashes[i] = (s >= 0 ? 0 : 1);
//cout << hashes[i] << endl;
// printf("s = %f, hash[%ld] = %d\n", s, i, hashes[i]);
}
return hashes;
}
SignedRandomProjection::~SignedRandomProjection() {
for (size_t i = 0; i < _numhashes; i++) {
delete[] _randBits[i];
delete[] _indices[i];
}
delete[] _randBits;
delete[] _indices;
}
//int * SignedRandomProjection::getHash(double * vector, int length)
//{
// // lenght should be = to _dim
// int * hashes = new int[_numhashes];
// for (size_t i = 0; i < _numhashes; i++)
// {
// hashes[i] = 0;
// for (size_t j = 0; j < _samSize; j++)
// {
// if(_randBits[i][j] >=0)
// hashes[i] += vector[_indices[i][j]];
// else
// hashes[i] -= vector[_indices[i][j]];
// }
// if (hashes[i] >= 0)
// hashes[i] = 0;
// else
// hashes[i] = 1;
// }
// return hashes;
//}