GreedySampler.cc

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#include "GreedySampler.h"
#include <algorithm>
#include <iostream>
#include <cmath>

float GreedySampler::sample() {
  if(ranges.size()==0) { // implies circular
    float r = full.span/2;
    float x = full.min+r;
    full.min-=r;
    ranges.push_back(full);
    return x;
  } else {
    pop_heap(ranges.begin(), ranges.end());
    float r2 = ranges.back().span / 2;
    float x = ranges.back().min + r2;
    ranges.back().span = r2;
    push_heap(ranges.begin(), ranges.end());
    ranges.push_back(range(x,r2));
    push_heap(ranges.begin(), ranges.end());
    if(x < reqMin) // implies circular with an initial removal
      x+=full.span;
    return x;
  }
}

float GreedySampler::resolution() {
  if(ranges.size()==0) {
    return full.span;
  } else {
    return ranges.front().span;
  }
}

void GreedySampler::remove(float x) {
  if(ranges.size()==0) { // implies circular
    full.min = normalize(x) - full.span;
    ranges.push_back(full);
  } else {
    if(circular)
      x = normalize(x);
    if(x <= full.min || full.min+full.span <= x) {
      if(x==full.min || x==full.min+full.span)
        return; // technically not in the 'sampled' range, but we'll ignore it
      throw std::range_error("takeSample(x): x out of the sampled range");
    }
    std::vector<range>::iterator it=ranges.begin();
    for(; it!=ranges.end(); ++it) {
      if(it->min <= x && x < it->min+it->span) {
        break;
      }
    }
#ifdef DEBUG
    if(it==ranges.end()) // this shouldn't be possible (already did range check), but just in case...
      throw std::runtime_error("takeSample(x): could not find x in sampled range");
#endif
    if(it->min == x)
      return; // duplicate sample, ignore it
    float r = x - it->min;
    range n(x, it->span - r);
    it->span = r;
    ranges.push_back(n);
    make_heap(ranges.begin(),ranges.end());
  }
}

void GreedySampler::reset() {
  full.min=reqMin;
  ranges.clear();
  if(!circular)
    ranges.push_back(full);
}

void GreedySampler::reset(float min, float max, bool circ) {
  reqMin = full.min = min;
  full.span = max-min;
  circular=circ;
  ranges.clear();
  if(!circular)
    ranges.push_back(full);
}

float GreedySampler::normalize(float value) {
  const float max = full.min + full.span;
  if ( value >= max ) {
    if ( value <= max+full.span ) {
      value -= full.span;
    } else { // use fmod only if necessary
      value = std::fmod(value,full.span);
      if( value > max )
        value -= full.span;
    }
  } else if ( value < full.min ) {
    if ( value >= full.min-full.span ) {
      value += full.span;
    } else { // use fmod only if necessary
      value = std::fmod(value,full.span);
      if( value <= full.min )
        value += full.span;
    }
  }
  return value;
}

std::ostream& operator<<(std::ostream& os, const GreedySampler& gs) {
  for(std::vector<GreedySampler::range>::const_iterator it=gs.ranges.begin(); it!=gs.ranges.end(); ++it)
    os << "(" << it->min << "," << (it->min+it->span) << ") ";
  return os << "\n";
}