/usr/include/opencv2/flann/lsh_table.h is in libopencv-flann-dev 2.4.9.1+dfsg1-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 | /***********************************************************************
* Software License Agreement (BSD License)
*
* Copyright 2008-2009 Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
* Copyright 2008-2009 David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
*
* THE BSD LICENSE
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*************************************************************************/
/***********************************************************************
* Author: Vincent Rabaud
*************************************************************************/
#ifndef OPENCV_FLANN_LSH_TABLE_H_
#define OPENCV_FLANN_LSH_TABLE_H_
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <limits.h>
// TODO as soon as we use C++0x, use the code in USE_UNORDERED_MAP
#ifdef __GXX_EXPERIMENTAL_CXX0X__
# define USE_UNORDERED_MAP 1
#else
# define USE_UNORDERED_MAP 0
#endif
#if USE_UNORDERED_MAP
#include <unordered_map>
#else
#include <map>
#endif
#include <math.h>
#include <stddef.h>
#include "dynamic_bitset.h"
#include "matrix.h"
namespace cvflann
{
namespace lsh
{
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/** What is stored in an LSH bucket
*/
typedef uint32_t FeatureIndex;
/** The id from which we can get a bucket back in an LSH table
*/
typedef unsigned int BucketKey;
/** A bucket in an LSH table
*/
typedef std::vector<FeatureIndex> Bucket;
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/** POD for stats about an LSH table
*/
struct LshStats
{
std::vector<unsigned int> bucket_sizes_;
size_t n_buckets_;
size_t bucket_size_mean_;
size_t bucket_size_median_;
size_t bucket_size_min_;
size_t bucket_size_max_;
size_t bucket_size_std_dev;
/** Each contained vector contains three value: beginning/end for interval, number of elements in the bin
*/
std::vector<std::vector<unsigned int> > size_histogram_;
};
/** Overload the << operator for LshStats
* @param out the streams
* @param stats the stats to display
* @return the streams
*/
inline std::ostream& operator <<(std::ostream& out, const LshStats& stats)
{
int w = 20;
out << "Lsh Table Stats:\n" << std::setw(w) << std::setiosflags(std::ios::right) << "N buckets : "
<< stats.n_buckets_ << "\n" << std::setw(w) << std::setiosflags(std::ios::right) << "mean size : "
<< std::setiosflags(std::ios::left) << stats.bucket_size_mean_ << "\n" << std::setw(w)
<< std::setiosflags(std::ios::right) << "median size : " << stats.bucket_size_median_ << "\n" << std::setw(w)
<< std::setiosflags(std::ios::right) << "min size : " << std::setiosflags(std::ios::left)
<< stats.bucket_size_min_ << "\n" << std::setw(w) << std::setiosflags(std::ios::right) << "max size : "
<< std::setiosflags(std::ios::left) << stats.bucket_size_max_;
// Display the histogram
out << std::endl << std::setw(w) << std::setiosflags(std::ios::right) << "histogram : "
<< std::setiosflags(std::ios::left);
for (std::vector<std::vector<unsigned int> >::const_iterator iterator = stats.size_histogram_.begin(), end =
stats.size_histogram_.end(); iterator != end; ++iterator) out << (*iterator)[0] << "-" << (*iterator)[1] << ": " << (*iterator)[2] << ", ";
return out;
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/** Lsh hash table. As its key is a sub-feature, and as usually
* the size of it is pretty small, we keep it as a continuous memory array.
* The value is an index in the corpus of features (we keep it as an unsigned
* int for pure memory reasons, it could be a size_t)
*/
template<typename ElementType>
class LshTable
{
public:
/** A container of all the feature indices. Optimized for space
*/
#if USE_UNORDERED_MAP
typedef std::unordered_map<BucketKey, Bucket> BucketsSpace;
#else
typedef std::map<BucketKey, Bucket> BucketsSpace;
#endif
/** A container of all the feature indices. Optimized for speed
*/
typedef std::vector<Bucket> BucketsSpeed;
/** Default constructor
*/
LshTable()
{
}
/** Default constructor
* Create the mask and allocate the memory
* @param feature_size is the size of the feature (considered as a ElementType[])
* @param key_size is the number of bits that are turned on in the feature
*/
LshTable(unsigned int /*feature_size*/, unsigned int /*key_size*/)
{
std::cerr << "LSH is not implemented for that type" << std::endl;
assert(0);
}
/** Add a feature to the table
* @param value the value to store for that feature
* @param feature the feature itself
*/
void add(unsigned int value, const ElementType* feature)
{
// Add the value to the corresponding bucket
BucketKey key = (lsh::BucketKey)getKey(feature);
switch (speed_level_) {
case kArray:
// That means we get the buckets from an array
buckets_speed_[key].push_back(value);
break;
case kBitsetHash:
// That means we can check the bitset for the presence of a key
key_bitset_.set(key);
buckets_space_[key].push_back(value);
break;
case kHash:
{
// That means we have to check for the hash table for the presence of a key
buckets_space_[key].push_back(value);
break;
}
}
}
/** Add a set of features to the table
* @param dataset the values to store
*/
void add(Matrix<ElementType> dataset)
{
#if USE_UNORDERED_MAP
buckets_space_.rehash((buckets_space_.size() + dataset.rows) * 1.2);
#endif
// Add the features to the table
for (unsigned int i = 0; i < dataset.rows; ++i) add(i, dataset[i]);
// Now that the table is full, optimize it for speed/space
optimize();
}
/** Get a bucket given the key
* @param key
* @return
*/
inline const Bucket* getBucketFromKey(BucketKey key) const
{
// Generate other buckets
switch (speed_level_) {
case kArray:
// That means we get the buckets from an array
return &buckets_speed_[key];
break;
case kBitsetHash:
// That means we can check the bitset for the presence of a key
if (key_bitset_.test(key)) return &buckets_space_.find(key)->second;
else return 0;
break;
case kHash:
{
// That means we have to check for the hash table for the presence of a key
BucketsSpace::const_iterator bucket_it, bucket_end = buckets_space_.end();
bucket_it = buckets_space_.find(key);
// Stop here if that bucket does not exist
if (bucket_it == bucket_end) return 0;
else return &bucket_it->second;
break;
}
}
return 0;
}
/** Compute the sub-signature of a feature
*/
size_t getKey(const ElementType* /*feature*/) const
{
std::cerr << "LSH is not implemented for that type" << std::endl;
assert(0);
return 1;
}
/** Get statistics about the table
* @return
*/
LshStats getStats() const;
private:
/** defines the speed fo the implementation
* kArray uses a vector for storing data
* kBitsetHash uses a hash map but checks for the validity of a key with a bitset
* kHash uses a hash map only
*/
enum SpeedLevel
{
kArray, kBitsetHash, kHash
};
/** Initialize some variables
*/
void initialize(size_t key_size)
{
const size_t key_size_lower_bound = 1;
//a value (size_t(1) << key_size) must fit the size_t type so key_size has to be strictly less than size of size_t
const size_t key_size_upper_bound = std::min(sizeof(BucketKey) * CHAR_BIT + 1, sizeof(size_t) * CHAR_BIT);
if (key_size < key_size_lower_bound || key_size >= key_size_upper_bound)
{
std::stringstream errorMessage;
errorMessage << "Invalid key_size (=" << key_size << "). Valid values for your system are " << key_size_lower_bound << " <= key_size < " << key_size_upper_bound << ".";
CV_Error(CV_StsBadArg, errorMessage.str());
}
speed_level_ = kHash;
key_size_ = (unsigned)key_size;
}
/** Optimize the table for speed/space
*/
void optimize()
{
// If we are already using the fast storage, no need to do anything
if (speed_level_ == kArray) return;
// Use an array if it will be more than half full
if (buckets_space_.size() > ((size_t(1) << key_size_) / 2)) {
speed_level_ = kArray;
// Fill the array version of it
buckets_speed_.resize(size_t(1) << key_size_);
for (BucketsSpace::const_iterator key_bucket = buckets_space_.begin(); key_bucket != buckets_space_.end(); ++key_bucket) buckets_speed_[key_bucket->first] = key_bucket->second;
// Empty the hash table
buckets_space_.clear();
return;
}
// If the bitset is going to use less than 10% of the RAM of the hash map (at least 1 size_t for the key and two
// for the vector) or less than 512MB (key_size_ <= 30)
if (((std::max(buckets_space_.size(), buckets_speed_.size()) * CHAR_BIT * 3 * sizeof(BucketKey)) / 10
>= (size_t(1) << key_size_)) || (key_size_ <= 32)) {
speed_level_ = kBitsetHash;
key_bitset_.resize(size_t(1) << key_size_);
key_bitset_.reset();
// Try with the BucketsSpace
for (BucketsSpace::const_iterator key_bucket = buckets_space_.begin(); key_bucket != buckets_space_.end(); ++key_bucket) key_bitset_.set(key_bucket->first);
}
else {
speed_level_ = kHash;
key_bitset_.clear();
}
}
/** The vector of all the buckets if they are held for speed
*/
BucketsSpeed buckets_speed_;
/** The hash table of all the buckets in case we cannot use the speed version
*/
BucketsSpace buckets_space_;
/** What is used to store the data */
SpeedLevel speed_level_;
/** If the subkey is small enough, it will keep track of which subkeys are set through that bitset
* That is just a speedup so that we don't look in the hash table (which can be mush slower that checking a bitset)
*/
DynamicBitset key_bitset_;
/** The size of the sub-signature in bits
*/
unsigned int key_size_;
// Members only used for the unsigned char specialization
/** The mask to apply to a feature to get the hash key
* Only used in the unsigned char case
*/
std::vector<size_t> mask_;
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Specialization for unsigned char
template<>
inline LshTable<unsigned char>::LshTable(unsigned int feature_size, unsigned int subsignature_size)
{
initialize(subsignature_size);
// Allocate the mask
mask_ = std::vector<size_t>((size_t)ceil((float)(feature_size * sizeof(char)) / (float)sizeof(size_t)), 0);
// A bit brutal but fast to code
std::vector<size_t> indices(feature_size * CHAR_BIT);
for (size_t i = 0; i < feature_size * CHAR_BIT; ++i) indices[i] = i;
std::random_shuffle(indices.begin(), indices.end());
// Generate a random set of order of subsignature_size_ bits
for (unsigned int i = 0; i < key_size_; ++i) {
size_t index = indices[i];
// Set that bit in the mask
size_t divisor = CHAR_BIT * sizeof(size_t);
size_t idx = index / divisor; //pick the right size_t index
mask_[idx] |= size_t(1) << (index % divisor); //use modulo to find the bit offset
}
// Set to 1 if you want to display the mask for debug
#if 0
{
size_t bcount = 0;
BOOST_FOREACH(size_t mask_block, mask_){
out << std::setw(sizeof(size_t) * CHAR_BIT / 4) << std::setfill('0') << std::hex << mask_block
<< std::endl;
bcount += __builtin_popcountll(mask_block);
}
out << "bit count : " << std::dec << bcount << std::endl;
out << "mask size : " << mask_.size() << std::endl;
return out;
}
#endif
}
/** Return the Subsignature of a feature
* @param feature the feature to analyze
*/
template<>
inline size_t LshTable<unsigned char>::getKey(const unsigned char* feature) const
{
// no need to check if T is dividable by sizeof(size_t) like in the Hamming
// distance computation as we have a mask
const size_t* feature_block_ptr = reinterpret_cast<const size_t*> ((const void*)feature);
// Figure out the subsignature of the feature
// Given the feature ABCDEF, and the mask 001011, the output will be
// 000CEF
size_t subsignature = 0;
size_t bit_index = 1;
for (std::vector<size_t>::const_iterator pmask_block = mask_.begin(); pmask_block != mask_.end(); ++pmask_block) {
// get the mask and signature blocks
size_t feature_block = *feature_block_ptr;
size_t mask_block = *pmask_block;
while (mask_block) {
// Get the lowest set bit in the mask block
size_t lowest_bit = mask_block & (-(ptrdiff_t)mask_block);
// Add it to the current subsignature if necessary
subsignature += (feature_block & lowest_bit) ? bit_index : 0;
// Reset the bit in the mask block
mask_block ^= lowest_bit;
// increment the bit index for the subsignature
bit_index <<= 1;
}
// Check the next feature block
++feature_block_ptr;
}
return subsignature;
}
template<>
inline LshStats LshTable<unsigned char>::getStats() const
{
LshStats stats;
stats.bucket_size_mean_ = 0;
if ((buckets_speed_.empty()) && (buckets_space_.empty())) {
stats.n_buckets_ = 0;
stats.bucket_size_median_ = 0;
stats.bucket_size_min_ = 0;
stats.bucket_size_max_ = 0;
return stats;
}
if (!buckets_speed_.empty()) {
for (BucketsSpeed::const_iterator pbucket = buckets_speed_.begin(); pbucket != buckets_speed_.end(); ++pbucket) {
stats.bucket_sizes_.push_back((lsh::FeatureIndex)pbucket->size());
stats.bucket_size_mean_ += pbucket->size();
}
stats.bucket_size_mean_ /= buckets_speed_.size();
stats.n_buckets_ = buckets_speed_.size();
}
else {
for (BucketsSpace::const_iterator x = buckets_space_.begin(); x != buckets_space_.end(); ++x) {
stats.bucket_sizes_.push_back((lsh::FeatureIndex)x->second.size());
stats.bucket_size_mean_ += x->second.size();
}
stats.bucket_size_mean_ /= buckets_space_.size();
stats.n_buckets_ = buckets_space_.size();
}
std::sort(stats.bucket_sizes_.begin(), stats.bucket_sizes_.end());
// BOOST_FOREACH(int size, stats.bucket_sizes_)
// std::cout << size << " ";
// std::cout << std::endl;
stats.bucket_size_median_ = stats.bucket_sizes_[stats.bucket_sizes_.size() / 2];
stats.bucket_size_min_ = stats.bucket_sizes_.front();
stats.bucket_size_max_ = stats.bucket_sizes_.back();
// TODO compute mean and std
/*float mean, stddev;
stats.bucket_size_mean_ = mean;
stats.bucket_size_std_dev = stddev;*/
// Include a histogram of the buckets
unsigned int bin_start = 0;
unsigned int bin_end = 20;
bool is_new_bin = true;
for (std::vector<unsigned int>::iterator iterator = stats.bucket_sizes_.begin(), end = stats.bucket_sizes_.end(); iterator
!= end; )
if (*iterator < bin_end) {
if (is_new_bin) {
stats.size_histogram_.push_back(std::vector<unsigned int>(3, 0));
stats.size_histogram_.back()[0] = bin_start;
stats.size_histogram_.back()[1] = bin_end - 1;
is_new_bin = false;
}
++stats.size_histogram_.back()[2];
++iterator;
}
else {
bin_start += 20;
bin_end += 20;
is_new_bin = true;
}
return stats;
}
// End the two namespaces
}
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#endif /* OPENCV_FLANN_LSH_TABLE_H_ */
|