opencv/modules/imgproc/src/lsh.cpp

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/*M///////////////////////////////////////////////////////////////////////////////////////
//
// IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
//
// By downloading, copying, installing or using the software you agree to this license.
// If you do not agree to this license, do not download, install,
// copy or use the software.
//
//
// Intel License Agreement
// For Open Source Computer Vision Library
//
// Copyright (C) 2009, Xavier Delacour, all rights reserved.
// Third party copyrights are property of their respective owners.
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// are permitted provided that the following conditions are met:
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// (including, but not limited to, procurement of substitute goods or services;
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// or tort (including negligence or otherwise) arising in any way out of
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//
//M*/
// 2009-01-12, Xavier Delacour <xavier.delacour@gmail.com>
// * hash perf could be improved
// * in particular, implement integer only (converted fixed from float input)
// * number of hash functions could be reduced (andoni paper)
// * redundant distance computations could be suppressed
// * rework CvLSHOperations interface-- move some of the loops into it to
// * allow efficient async storage
// Datar, M., Immorlica, N., Indyk, P., and Mirrokni, V. S. 2004. Locality-sensitive hashing
// scheme based on p-stable distributions. In Proceedings of the Twentieth Annual Symposium on
// Computational Geometry (Brooklyn, New York, USA, June 08 - 11, 2004). SCG '04. ACM, New York,
// NY, 253-262. DOI= http://doi.acm.org/10.1145/997817.997857
#include "precomp.hpp"
#include <math.h>
#include <vector>
#include <algorithm>
#include <limits>
template <class T>
class memory_hash_ops : public CvLSHOperations {
int d;
std::vector<T> data;
std::vector<int> free_data;
struct node {
int i, h2, next;
};
std::vector<node> nodes;
std::vector<int> free_nodes;
std::vector<int> bins;
public:
memory_hash_ops(int _d, int n) : d(_d) {
bins.resize(n, -1);
}
virtual int vector_add(const void* _p) {
const T* p = (const T*)_p;
int i;
if (free_data.empty()) {
i = (int)data.size();
data.insert(data.end(), d, 0);
} else {
i = free_data.end()[-1];
free_data.pop_back();
}
std::copy(p, p + d, data.begin() + i);
return i / d;
}
virtual void vector_remove(int i) {
free_data.push_back(i * d);
}
virtual const void* vector_lookup(int i) {
return &data[i * d];
}
virtual void vector_reserve(int n) {
data.reserve(n * d);
}
virtual unsigned int vector_count() {
return (unsigned)(data.size() / d - free_data.size());
}
virtual void hash_insert(lsh_hash h, int /*l*/, int i) {
int ii;
if (free_nodes.empty()) {
ii = (int)nodes.size();
nodes.push_back(node());
} else {
ii = free_nodes.end()[-1];
free_nodes.pop_back();
}
node& n = nodes[ii];
int h1 = h.h1 % bins.size();
n.i = i;
n.h2 = h.h2;
n.next = bins[h1];
bins[h1] = ii;
}
virtual void hash_remove(lsh_hash h, int /*l*/, int i) {
int h1 = h.h1 % bins.size();
for (int ii = bins[h1], iin, iip = -1; ii != -1; iip = ii, ii = iin) {
iin = nodes[ii].next;
if (nodes[ii].h2 == h.h2 && nodes[ii].i == i) {
free_nodes.push_back(ii);
if (iip == -1)
bins[h1] = iin;
else
nodes[iip].next = iin;
}
}
}
virtual int hash_lookup(lsh_hash h, int /*l*/, int* ret_i, int ret_i_max) {
int h1 = h.h1 % bins.size();
int k = 0;
for (int ii = bins[h1]; ii != -1 && k < ret_i_max; ii = nodes[ii].next)
if (nodes[ii].h2 == h.h2)
ret_i[k++] = nodes[ii].i;
return k;
}
};
template <class T,int cvtype>
class pstable_l2_func {
CvMat *a, *b, *r1, *r2;
int d, k;
double r;
pstable_l2_func(const pstable_l2_func& x);
pstable_l2_func& operator= (const pstable_l2_func& rhs);
public:
typedef T scalar_type;
typedef T accum_type;
pstable_l2_func(int _d, int _k, double _r, CvRNG& rng)
: d(_d), k(_k), r(_r) {
assert(sizeof(T) == CV_ELEM_SIZE1(cvtype));
a = cvCreateMat(k, d, cvtype);
b = cvCreateMat(k, 1, cvtype);
r1 = cvCreateMat(k, 1, CV_32SC1);
r2 = cvCreateMat(k, 1, CV_32SC1);
cvRandArr(&rng, a, CV_RAND_NORMAL, cvScalar(0), cvScalar(1));
cvRandArr(&rng, b, CV_RAND_UNI, cvScalar(0), cvScalar(r));
cvRandArr(&rng, r1, CV_RAND_UNI,
cvScalar(std::numeric_limits<int>::min()),
cvScalar(std::numeric_limits<int>::max()));
cvRandArr(&rng, r2, CV_RAND_UNI,
cvScalar(std::numeric_limits<int>::min()),
cvScalar(std::numeric_limits<int>::max()));
}
~pstable_l2_func() {
cvReleaseMat(&a);
cvReleaseMat(&b);
cvReleaseMat(&r1);
cvReleaseMat(&r2);
}
// * factor all L functions into this (reduces number of matrices to 4 total;
// * simpler syntax in lsh_table). give parameter l here that tells us which
// * row to use etc.
lsh_hash operator() (const T* x) const {
const T* aj = (const T*)a->data.ptr;
const T* bj = (const T*)b->data.ptr;
lsh_hash h;
h.h1 = h.h2 = 0;
for (int j = 0; j < k; ++j) {
accum_type s = 0;
for (int jj = 0; jj < d; ++jj)
s += aj[jj] * x[jj];
s += *bj;
s = accum_type(s/r);
int si = int(s);
h.h1 += r1->data.i[j] * si;
h.h2 += r2->data.i[j] * si;
aj += d;
bj++;
}
return h;
}
accum_type distance(const T* p, const T* q) const {
accum_type s = 0;
for (int j = 0; j < d; ++j) {
accum_type d1 = p[j] - q[j];
s += d1 * d1;
}
return s;
}
};
template <class H>
class lsh_table {
public:
typedef typename H::scalar_type scalar_type;
typedef typename H::accum_type accum_type;
private:
std::vector<H*> g;
CvLSHOperations* ops;
int d, L, k;
double r;
static accum_type comp_dist(const std::pair<int,accum_type>& x,
const std::pair<int,accum_type>& y) {
return x.second < y.second;
}
lsh_table(const lsh_table& x);
lsh_table& operator= (const lsh_table& rhs);
public:
lsh_table(CvLSHOperations* _ops, int _d, int Lval, int _k, double _r, CvRNG& rng)
: ops(_ops), d(_d), L(Lval), k(_k), r(_r) {
g.resize(L);
for (int j = 0; j < L; ++j)
g[j] = new H(d, k, r, rng);
}
~lsh_table() {
for (int j = 0; j < L; ++j)
delete g[j];
delete ops;
}
int dims() const {
return d;
}
unsigned int size() const {
return ops->vector_count();
}
void add(const scalar_type* data, int n, int* ret_indices = 0) {
for (int j=0;j<n;++j) {
const scalar_type* x = data+j*d;
int i = ops->vector_add(x);
if (ret_indices)
ret_indices[j] = i;
for (int l = 0; l < L; ++l) {
lsh_hash h = (*g[l])(x);
ops->hash_insert(h, l, i);
}
}
}
void remove(const int* indices, int n) {
for (int j = 0; j < n; ++j) {
int i = indices[n];
const scalar_type* x = (const scalar_type*)ops->vector_lookup(i);
for (int l = 0; l < L; ++l) {
lsh_hash h = (*g[l])(x);
ops->hash_remove(h, l, i);
}
ops->vector_remove(i);
}
}
void query(const scalar_type* q, int k0, int emax, double* dist, int* results) {
int* tmp = (int*)cvStackAlloc(sizeof(int) * emax);
typedef std::pair<int, accum_type> dr_type; // * swap int and accum_type here, for naming consistency
dr_type* dr = (dr_type*)cvStackAlloc(sizeof(dr_type) * k0);
int k1 = 0;
// * handle k0 >= emax, in which case don't track max distance
for (int l = 0; l < L && emax > 0; ++l) {
lsh_hash h = (*g[l])(q);
int m = ops->hash_lookup(h, l, tmp, emax);
for (int j = 0; j < m && emax > 0; ++j, --emax) {
int i = tmp[j];
const scalar_type* p = (const scalar_type*)ops->vector_lookup(i);
accum_type pd = (*g[l]).distance(p, q);
if (k1 < k0) {
dr[k1++] = std::make_pair(i, pd);
std::push_heap(dr, dr + k1, comp_dist);
} else if (pd < dr[0].second) {
std::pop_heap(dr, dr + k0, comp_dist);
dr[k0 - 1] = std::make_pair(i, pd);
std::push_heap(dr, dr + k0, comp_dist);
}
}
}
for (int j = 0; j < k1; ++j)
dist[j] = dr[j].second, results[j] = dr[j].first;
std::fill(dist + k1, dist + k0, 0);
std::fill(results + k1, results + k0, -1);
}
void query(const scalar_type* data, int n, int k0, int emax, double* dist, int* results) {
for (int j = 0; j < n; ++j) {
query(data, k0, emax, dist, results);
data += d; // * this may not agree with step for some scalar_types
dist += k0;
results += k0;
}
}
};
typedef lsh_table<pstable_l2_func<float, CV_32FC1> > lsh_pstable_l2_32f;
typedef lsh_table<pstable_l2_func<double, CV_64FC1> > lsh_pstable_l2_64f;
struct CvLSH {
int type;
union {
lsh_pstable_l2_32f* lsh_32f;
lsh_pstable_l2_64f* lsh_64f;
} u;
};
CvLSH* cvCreateLSH(CvLSHOperations* ops, int d, int L, int k, int type, double r, int64 seed) {
CvLSH* lsh = 0;
CvRNG rng = cvRNG(seed);
if (type != CV_32FC1 && type != CV_64FC1)
CV_Error(CV_StsUnsupportedFormat, "vectors must be either CV_32FC1 or CV_64FC1");
lsh = new CvLSH;
lsh->type = type;
switch (type) {
case CV_32FC1: lsh->u.lsh_32f = new lsh_pstable_l2_32f(ops, d, L, k, r, rng); break;
case CV_64FC1: lsh->u.lsh_64f = new lsh_pstable_l2_64f(ops, d, L, k, r, rng); break;
}
return lsh;
}
CvLSH* cvCreateMemoryLSH(int d, int n, int L, int k, int type, double r, int64 seed) {
CvLSHOperations* ops = 0;
switch (type) {
case CV_32FC1: ops = new memory_hash_ops<float>(d,n); break;
case CV_64FC1: ops = new memory_hash_ops<double>(d,n); break;
}
return cvCreateLSH(ops, d, L, k, type, r, seed);
}
void cvReleaseLSH(CvLSH** lsh) {
switch ((*lsh)->type) {
case CV_32FC1: delete (*lsh)->u.lsh_32f; break;
case CV_64FC1: delete (*lsh)->u.lsh_64f; break;
default: assert(0);
}
delete *lsh;
*lsh = 0;
}
unsigned int LSHSize(CvLSH* lsh) {
switch (lsh->type) {
case CV_32FC1: return lsh->u.lsh_32f->size(); break;
case CV_64FC1: return lsh->u.lsh_64f->size(); break;
default: assert(0);
}
return 0;
}
void cvLSHAdd(CvLSH* lsh, const CvMat* data, CvMat* indices) {
int dims, n;
int* ret_indices = 0;
switch (lsh->type) {
case CV_32FC1: dims = lsh->u.lsh_32f->dims(); break;
case CV_64FC1: dims = lsh->u.lsh_64f->dims(); break;
default: assert(0); return;
}
n = data->rows;
if (dims != data->cols)
CV_Error(CV_StsBadSize, "data must be n x d, where d is what was used to construct LSH");
if (CV_MAT_TYPE(data->type) != lsh->type)
CV_Error(CV_StsUnsupportedFormat, "type of data and constructed LSH must agree");
if (indices) {
if (CV_MAT_TYPE(indices->type) != CV_32SC1)
CV_Error(CV_StsUnsupportedFormat, "indices must be CV_32SC1");
if (indices->rows * indices->cols != n)
CV_Error(CV_StsBadSize, "indices must be n x 1 or 1 x n for n x d data");
ret_indices = indices->data.i;
}
switch (lsh->type) {
case CV_32FC1: lsh->u.lsh_32f->add(data->data.fl, n, ret_indices); break;
case CV_64FC1: lsh->u.lsh_64f->add(data->data.db, n, ret_indices); break;
default: assert(0); return;
}
}
void cvLSHRemove(CvLSH* lsh, const CvMat* indices) {
int n;
if (CV_MAT_TYPE(indices->type) != CV_32SC1)
CV_Error(CV_StsUnsupportedFormat, "indices must be CV_32SC1");
n = indices->rows * indices->cols;
switch (lsh->type) {
case CV_32FC1: lsh->u.lsh_32f->remove(indices->data.i, n); break;
case CV_64FC1: lsh->u.lsh_64f->remove(indices->data.i, n); break;
default: assert(0); return;
}
}
void cvLSHQuery(CvLSH* lsh, const CvMat* data, CvMat* indices, CvMat* dist, int k, int emax) {
int dims;
switch (lsh->type) {
case CV_32FC1: dims = lsh->u.lsh_32f->dims(); break;
case CV_64FC1: dims = lsh->u.lsh_64f->dims(); break;
default: assert(0); return;
}
if (k<1)
CV_Error(CV_StsOutOfRange, "k must be positive");
if (CV_MAT_TYPE(data->type) != lsh->type)
CV_Error(CV_StsUnsupportedFormat, "type of data and constructed LSH must agree");
if (dims != data->cols)
CV_Error(CV_StsBadSize, "data must be n x d, where d is what was used to construct LSH");
if (dist->rows != data->rows || dist->cols != k)
CV_Error(CV_StsBadSize, "dist must be n x k for n x d data");
if (dist->rows != indices->rows || dist->cols != indices->cols)
CV_Error(CV_StsBadSize, "dist and indices must be same size");
if (CV_MAT_TYPE(dist->type) != CV_64FC1)
CV_Error(CV_StsUnsupportedFormat, "dist must be CV_64FC1");
if (CV_MAT_TYPE(indices->type) != CV_32SC1)
CV_Error(CV_StsUnsupportedFormat, "indices must be CV_32SC1");
switch (lsh->type) {
case CV_32FC1: lsh->u.lsh_32f->query(data->data.fl, data->rows,
k, emax, dist->data.db, indices->data.i); break;
case CV_64FC1: lsh->u.lsh_64f->query(data->data.db, data->rows,
k, emax, dist->data.db, indices->data.i); break;
default: assert(0); return;
}
}