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;
230 template<
class Random = MersenneTwister >
248 typedef std::map<IndexType, IndexArrayType> StrataIndicesType;
249 typedef std::map<IndexType, int> StrataSizesType;
253 static const int oobInvalid = -1;
255 int total_count_, sample_size_;
256 mutable int current_oob_count_;
257 StrataIndicesType strata_indices_;
258 StrataSizesType strata_sample_size_;
262 Random
const & random_;
265 void initStrataCount()
270 int strata_total_count = strata_sample_size *
strataCount();
272 for(StrataIndicesType::iterator i = strata_indices_.begin();
273 i != strata_indices_.end(); ++i)
275 if(strata_total_count > sample_size_)
277 strata_sample_size_[i->first] = strata_sample_size - 1;
278 --strata_total_count;
282 strata_sample_size_[i->first] = strata_sample_size;
296 Random
const & rnd = Random(RandomSeed))
297 : total_count_(totalCount),
298 sample_size_(opt.sample_size == 0
299 ? (int)(std::
ceil(total_count_ * opt.sample_proportion))
301 current_oob_count_(oobInvalid),
302 current_sample_(sample_size_),
303 current_oob_sample_(total_count_),
304 is_used_(total_count_),
308 vigra_precondition(opt.sample_with_replacement || sample_size_ <= total_count_,
309 "Sampler(): Cannot draw without replacement when data size is smaller than sample count.");
311 vigra_precondition(!opt.stratified_sampling,
312 "Sampler(): Stratified sampling requested, but no strata given.");
315 strata_indices_[0].resize(total_count_);
316 for(
int i=0; i<total_count_; ++i)
317 strata_indices_[0][i] = i;
333 template <
class Iterator>
335 Random
const & rnd = Random(RandomSeed))
336 : total_count_(strataEnd - strataBegin),
337 sample_size_(opt.sample_size == 0
338 ? (int)(std::
ceil(total_count_ * opt.sample_proportion))
340 current_oob_count_(oobInvalid),
341 current_sample_(sample_size_),
342 current_oob_sample_(total_count_),
343 is_used_(total_count_),
347 vigra_precondition(opt.sample_with_replacement || sample_size_ <= total_count_,
348 "Sampler(): Cannot draw without replacement when data size is smaller than sample count.");
351 if(opt.stratified_sampling)
353 for(
int i = 0; strataBegin != strataEnd; ++i, ++strataBegin)
355 strata_indices_[*strataBegin].push_back(i);
360 strata_indices_[0].resize(total_count_);
361 for(
int i=0; i<total_count_; ++i)
362 strata_indices_[0][i] = i;
365 vigra_precondition(sample_size_ >= (
int)strata_indices_.size(),
366 "Sampler(): Requested sample count must be at least as large as the number of strata.");
377 return current_sample_[k];
411 return strata_indices_.size();
419 return options_.stratified_sampling;
426 return options_.sample_with_replacement;
433 return current_sample_;
441 if(current_oob_count_ == oobInvalid)
443 current_oob_count_ = 0;
444 for(
int i = 0; i<total_count_; ++i)
448 current_oob_sample_[current_oob_count_] = i;
449 ++current_oob_count_;
453 return current_oob_sample_.
subarray(0, current_oob_count_);
455 IsUsedArrayType
const & is_used()
const
462 template<
class Random>
465 current_oob_count_ = oobInvalid;
466 is_used_.init(
false);
468 if(options_.sample_with_replacement)
472 StrataIndicesType::iterator iter;
473 for(iter = strata_indices_.begin(); iter != strata_indices_.end(); ++iter)
476 int stratum_size = iter->second.size();
477 for(
int i = 0; i < (int)strata_sample_size_[iter->first]; ++i, ++j)
479 current_sample_[j] = iter->second[random_.uniformInt(stratum_size)];
480 is_used_[current_sample_[j]] =
true;
488 StrataIndicesType::iterator iter;
489 for(iter = strata_indices_.begin(); iter != strata_indices_.end(); ++iter)
492 int stratum_size = iter->second.size();
493 for(
int i = 0; i < (int)strata_sample_size_[iter->first]; ++i, ++j)
495 std::swap(iter->second[i], iter->second[i+ random_.uniformInt(stratum_size - i)]);
496 current_sample_[j] = iter->second[i];
497 is_used_[current_sample_[j]] =
true;
503 template<
class Random =RandomTT800 >
508 typedef Int32 IndexType;
510 IndexArrayType used_indices_;
515 PoissonSampler(
double lambda,IndexType minIndex,IndexType maxIndex)
523 used_indices_.clear();
525 for(i=minIndex;i<maxIndex;++i)
530 double L=
exp(-lambda);
534 p*=randfloat.uniform53();
541 used_indices_.push_back(i);
547 IndexType
const & operator[](
int in)
const
549 return used_indices_[in];
552 int numOfSamples()
const
554 return used_indices_.size();