nearest_neighbor_classifier.cpp

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// Copyright (c) 2012, 2019 Scott Niekum, Joshua Whitley
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#include "ml_classifiers/nearest_neighbor_classifier.hpp"
#include <pluginlib/class_list_macros.hpp>

#include <string>
#include <vector>
#include <cmath>

PLUGINLIB_EXPORT_CLASS(ml_classifiers::NearestNeighborClassifier, ml_classifiers::Classifier)

namespace ml_classifiers
{

NearestNeighborClassifier::NearestNeighborClassifier() {}

NearestNeighborClassifier::~NearestNeighborClassifier() {}

void NearestNeighborClassifier::save(const std::string filename) {}

bool NearestNeighborClassifier::load(const std::string filename)
{
  return false;
}

void NearestNeighborClassifier::addTrainingPoint(
  std::string target_class, const std::vector<double> point)
{
  class_data[target_class].push_back(point);
}

void NearestNeighborClassifier::train() {}

void NearestNeighborClassifier::clear()
{
  class_data.clear();
}

std::string NearestNeighborClassifier::classifyPoint(const std::vector<double> point)
{
  size_t dims = point.size();
  double min_diff = 0;
  std::string ans;
  bool first = true;

  for (ClassMap::iterator iter = class_data.begin(); iter != class_data.end(); iter++) {
    std::string cname = iter->first;
    CPointList cpl = iter->second;

    for (size_t i = 0; i < cpl.size(); i++) {
      double diff = 0;
      for (size_t j = 0; j < dims; j++) {
        diff += std::fabs(cpl[i][j] - point[j]);
      }

      if (first) {
        first = false;
        min_diff = diff;
        ans = cname;
      } else if (diff < min_diff) {
        min_diff = diff;
        ans = cname;
      }
    }
  }

  return ans;
}

}  // namespace ml_classifiers