variancepartitioner.cpp

来自「dysii是一款非常出色的滤波函数库」· C++ 代码 · 共 49 行

#include "VariancePartitioner.hpp"

using namespace indii::ml::aux;

VariancePartitioner::~VariancePartitioner() {
  //
}

void VariancePartitioner::init(Partitioner::points& xws) {
  /* pre-condition */
  assert (xws.size() >= 2);

  const unsigned int N = xws.front()->x.size();
  Partitioner::points::iterator iter, end;

  double W = 0.0;   // total weight 
  vector mu(N), sigma(N);  // mean, variance

  /* calculate mean and variance */
  mu.clear();
  sigma.clear();
  iter = xws.begin();
  end = xws.end();
  while (iter != end) {
    W += (*iter)->w;
    noalias(mu) += (*iter)->w * (*iter)->x;
    noalias(sigma) += (*iter)->w * element_prod((*iter)->x, (*iter)->x);
    iter++;
  }
  mu /= W;
  sigma /= W;
  noalias(sigma) -= element_prod(mu, mu);

  /* select dimension of highest variance */
  this->index = index_norm_inf(sigma);
  
  /* split on mean of given dimension */
  this->value = mu(index);
}

Partitioner::Partition VariancePartitioner::assign(const aux::vector& x) {
  if (x(index) <= value) {
    return Partitioner::LEFT;
  } else {
    return Partitioner::RIGHT;
  }
}