36 #ifndef VIGRA_SAMPLING_HXX
37 #define VIGRA_SAMPLING_HXX
39 #include "array_vector.hxx"
70 double sample_proportion;
71 unsigned int sample_size;
72 bool sample_with_replacement;
73 bool stratified_sampling;
76 : sample_proportion(1.0),
78 sample_with_replacement(
true),
79 stratified_sampling(
false)
88 sample_with_replacement = in;
98 sample_with_replacement = !in;
128 vigra_precondition(proportion >= 0.0,
129 "SamplerOptions::sampleProportion(): argument must not be negative.");
130 sample_proportion = proportion;
146 stratified_sampling = in;
232 template<
class Random = MersenneTwister >
250 typedef std::map<IndexType, IndexArrayType> StrataIndicesType;
251 typedef std::map<IndexType, int> StrataSizesType;
255 static const int oobInvalid = -1;
257 int total_count_, sample_size_;
258 mutable int current_oob_count_;
259 StrataIndicesType strata_indices_;
260 StrataSizesType strata_sample_size_;
264 Random
const & random_;
267 void initStrataCount()
272 int strata_total_count = strata_sample_size *
strataCount();
274 for(StrataIndicesType::iterator i = strata_indices_.begin();
275 i != strata_indices_.end(); ++i)
277 if(strata_total_count > sample_size_)
279 strata_sample_size_[i->first] = strata_sample_size - 1;
280 --strata_total_count;
284 strata_sample_size_[i->first] = strata_sample_size;
298 Random
const & rnd = Random(RandomSeed))
299 : total_count_(totalCount),
300 sample_size_(opt.sample_size == 0
301 ? (int)(std::
ceil(total_count_ * opt.sample_proportion))
303 current_oob_count_(oobInvalid),
304 current_sample_(sample_size_),
305 current_oob_sample_(total_count_),
306 is_used_(total_count_),
310 vigra_precondition(opt.sample_with_replacement || sample_size_ <= total_count_,
311 "Sampler(): Cannot draw without replacement when data size is smaller than sample count.");
313 vigra_precondition(!opt.stratified_sampling,
314 "Sampler(): Stratified sampling requested, but no strata given.");
317 strata_indices_[0].resize(total_count_);
318 for(
int i=0; i<total_count_; ++i)
319 strata_indices_[0][i] = i;
335 template <
class Iterator>
337 Random
const & rnd = Random(RandomSeed))
338 : total_count_(strataEnd - strataBegin),
339 sample_size_(opt.sample_size == 0
340 ? (int)(std::
ceil(total_count_ * opt.sample_proportion))
342 current_oob_count_(oobInvalid),
343 current_sample_(sample_size_),
344 current_oob_sample_(total_count_),
345 is_used_(total_count_),
349 vigra_precondition(opt.sample_with_replacement || sample_size_ <= total_count_,
350 "Sampler(): Cannot draw without replacement when data size is smaller than sample count.");
353 if(opt.stratified_sampling)
355 for(
int i = 0; strataBegin != strataEnd; ++i, ++strataBegin)
357 strata_indices_[*strataBegin].push_back(i);
362 strata_indices_[0].resize(total_count_);
363 for(
int i=0; i<total_count_; ++i)
364 strata_indices_[0][i] = i;
367 vigra_precondition(sample_size_ >= (
int)strata_indices_.size(),
368 "Sampler(): Requested sample count must be at least as large as the number of strata.");
379 return current_sample_[k];
413 return strata_indices_.size();
421 return options_.stratified_sampling;
428 return options_.sample_with_replacement;
435 return current_sample_;
443 if(current_oob_count_ == oobInvalid)
445 current_oob_count_ = 0;
446 for(
int i = 0; i<total_count_; ++i)
450 current_oob_sample_[current_oob_count_] = i;
451 ++current_oob_count_;
455 return current_oob_sample_.
subarray(0, current_oob_count_);
457 IsUsedArrayType
const & is_used()
const
464 template<
class Random>
467 current_oob_count_ = oobInvalid;
468 is_used_.init(
false);
470 if(options_.sample_with_replacement)
474 StrataIndicesType::iterator iter;
475 for(iter = strata_indices_.begin(); iter != strata_indices_.end(); ++iter)
478 int stratum_size = iter->second.size();
479 for(
int i = 0; i < (int)strata_sample_size_[iter->first]; ++i, ++j)
481 current_sample_[j] = iter->second[random_.uniformInt(stratum_size)];
482 is_used_[current_sample_[j]] =
true;
490 StrataIndicesType::iterator iter;
491 for(iter = strata_indices_.begin(); iter != strata_indices_.end(); ++iter)
494 int stratum_size = iter->second.size();
495 for(
int i = 0; i < (int)strata_sample_size_[iter->first]; ++i, ++j)
497 std::swap(iter->second[i], iter->second[i+ random_.uniformInt(stratum_size - i)]);
498 current_sample_[j] = iter->second[i];
499 is_used_[current_sample_[j]] =
true;
505 template<
class Random =RandomTT800 >
510 typedef Int32 IndexType;
512 IndexArrayType used_indices_;
517 PoissonSampler(
double lambda,IndexType minIndex,IndexType maxIndex)
525 used_indices_.clear();
527 for(i=minIndex;i<maxIndex;++i)
532 double L=
exp(-lambda);
536 p*=randfloat.uniform53();
543 used_indices_.push_back(i);
549 IndexType
const & operator[](
int in)
const
551 return used_indices_[in];
554 int numOfSamples()
const
556 return used_indices_.size();