C++ distances函数代码示例

		::rl::math::Vector
		SchmersalLss300::getDistances() const
		{
			assert(this->isConnected());
			
			::rl::math::Vector distances(this->getDistancesCount());
			
			::rl::math::Real scale = static_cast< ::rl::math::Real>(0.01);
			::std::uint16_t count = Endian::hostWord(this->data[8], this->data[7]);
			::std::uint8_t mask = 0x1F;
			
			for (::std::size_t i = 0; i < count; ++i)
			{
				if (this->data[10 + i * 2] & 32)
				{
					distances(i) = ::std::numeric_limits< ::rl::math::Real>::quiet_NaN();
				}
				else
				{
					distances(i) = Endian::hostWord(this->data[10 + i * 2] & mask, this->data[9 + i * 2]);
					distances(i) *= scale;
				}
			}
			
			return distances;
		}

void ClassicalScaling::run( PointWiseMapping* mymap ){
   // Retrieve the distances from the dimensionality reduction object
   double half=(-0.5); Matrix<double> distances( half*mymap->modifyDmat() ); 
 
   // Apply centering transtion
   unsigned n=distances.nrows(); double sum;
   // First HM
   for(unsigned i=0;i<n;++i){
       sum=0; for(unsigned j=0;j<n;++j) sum+=distances(i,j);
       for(unsigned j=0;j<n;++j) distances(i,j) -= sum/n;
   }
   // Now (HM)H
   for(unsigned i=0;i<n;++i){
      sum=0; for(unsigned j=0;j<n;++j) sum+=distances(j,i);
      for(unsigned j=0;j<n;++j) distances(j,i) -= sum/n; 
   }

   // Diagonalize matrix
   std::vector<double> eigval(n); Matrix<double> eigvec(n,n);
   diagMat( distances, eigval, eigvec );

   // Pass final projections to map object
   for(unsigned i=0;i<n;++i){
      for(unsigned j=0;j<mymap->getNumberOfProperties();++j) mymap->setProjectionCoordinate( i, j, sqrt(eigval[n-1-j])*eigvec(n-1-j,i) ); 
   }
}

void NeighborSearchRules<
    SortPolicy,
    MetricType,
    TreeType>::
UpdateAfterRecursion(TreeType& queryNode, TreeType& /* referenceNode */)
{
  // Find the worst distance that the children found (including any points), and
  // update the bound accordingly.
  double worstDistance = SortPolicy::BestDistance();

  // First look through children nodes.
  for (size_t i = 0; i < queryNode.NumChildren(); ++i)
  {
    if (SortPolicy::IsBetter(worstDistance, queryNode.Child(i).Stat().Bound()))
      worstDistance = queryNode.Child(i).Stat().Bound();
  }

  // Now look through children points.
  for (size_t i = 0; i < queryNode.NumPoints(); ++i)
  {
    if (SortPolicy::IsBetter(worstDistance,
        distances(distances.n_rows - 1, queryNode.Point(i))))
      worstDistance = distances(distances.n_rows - 1, queryNode.Point(i));
  }

  // Take the worst distance from all of these, and update our bound to reflect
  // that.
  queryNode.Stat().Bound() = worstDistance;
}

/**
 * Returns a vector of distances between the points in R and point y 
 */
vec GreedyMaxMinDesign::dist(mat R, vec y)
{
    vec distances(R.rows());
    
    // For each point x in R
    for (int i=0; i<R.rows(); i++) {
        vec x = R.get_row(i);
        distances(i) = weightedSquareNorm(x-y);
    }
    
    return distances;
}

void CartesianCoordinatesTest::distanceMatrix()
{
    chemkit::CartesianCoordinates coordinates(4);
    coordinates.setPosition(0, chemkit::Point3(1, 0, 0));
    coordinates.setPosition(1, chemkit::Point3(2, 0, 0));
    coordinates.setPosition(2, chemkit::Point3(0, 5, 0));
    coordinates.setPosition(3, chemkit::Point3(10, 5, 2));

    chemkit::Matrix distances = coordinates.distanceMatrix();
    QVERIFY(distances.rows() == 4);
    QVERIFY(distances.cols() == 4);
    QCOMPARE(qRound(distances(0, 0)), 0);
    QCOMPARE(qRound(distances(0, 1)), 1);
    QCOMPARE(qRound(distances(1, 0)), 1);
}

size_t closest_point_index_rayOMP(const pcl::PointCloud<PointT>& cloud,
                                  const Eigen::Vector3f& direction_pre,
                                  const Eigen::Vector3f& line_pt,
                                  double& distance_to_ray) {
    Eigen::Vector3f direction = direction_pre / direction_pre.norm();
    PointT point;
    std::vector<double> distances(cloud.points.size(), 10);  // Initialize to value 10
// Generate a vector of distances
    #pragma omp parallel for
    for (size_t index = 0; index < cloud.points.size(); index++) {
        point = cloud.points[index];

        Eigen::Vector3f cloud_pt(point.x, point.y, point.z);
        Eigen::Vector3f difference = (line_pt - cloud_pt);
        // https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line#Vector_formulation
        double distance = (difference - (difference.dot(direction) * direction)).norm();
        distances[index] = distance;
    }

    double min_distance = std::numeric_limits<double>::infinity();
    size_t min_index = 0;
    // Find index of maximum (TODO: Figure out how to OMP this)
    for (size_t index = 0; index < cloud.points.size(); index++) {
        const double distance = distances[index];
        if (distance < min_distance) {
            min_distance = distance;
            min_index = index;
        }
    }

    distance_to_ray = min_distance;

    return (min_index);
}

static void kmeans_center_multiple_restarts(
    unsigned nb_restarts, cluster_t nb_center,
    void (*center_init_f)(cluster_t, histogram_c &, dataset_t &, nbgen &),
    histogram_c &center, dataset_t &dataset, nbgen &rng) {
  std::vector<histogram_c> center_c(nb_restarts);
  for (unsigned i = 0; i < nb_restarts; ++i)
    center_init_f(nb_center, center_c[i], dataset, rng);

  unsigned nb_features = dataset[0].histogram.size();
  std::vector<double> cluster_dists(nb_restarts);
  for (unsigned r = 0; r < nb_restarts; ++r) {
    double sum = 0;
    unsigned count = 0;
    std::vector<double> distances(nb_center, 0);
    for (unsigned i = 0; i < nb_center; ++i) {
      for (unsigned j = 0; j < nb_center; ++j) {
        if (j == i)
          continue;
        double dist = l2_distance(center_c[r][i], center_c[r][j], nb_features);
        distances[i] += dist;
        ++count;
      }
      sum += distances[i];
    }
    cluster_dists[r] = sum / count;
    // printf("restart:%u -> %f\n", r, cluster_dists[r]);
  }
  size_t max_cluster = std::distance(
      cluster_dists.begin(),
      std::max_element(cluster_dists.begin(), cluster_dists.end()));
  // printf("min center index: %zu\n", max_cluster);
  center = center_c[max_cluster];
}

void
PolycrystalReducedIC::initialSetup()
{
 //Set up domain bounds with mesh tools
  for (unsigned int i = 0; i < LIBMESH_DIM; i++)
  {
    _bottom_left(i) = _mesh.getMinInDimension(i);
    _top_right(i) = _mesh.getMaxInDimension(i);
  }
  _range = _top_right - _bottom_left;

  if (_op_num > _grain_num)
     mooseError("ERROR in PolycrystalReducedIC: Number of order parameters (op_num) can't be larger than the number of grains (grain_num)");

  MooseRandom::seed(_rand_seed);

  //Randomly generate the centers of the individual grains represented by the Voronoi tesselation
  _centerpoints.resize(_grain_num);
  _assigned_op.resize(_grain_num);
  std::vector<Real> distances(_grain_num);

  //Assign actual center point positions
  for (unsigned int grain = 0; grain < _grain_num; grain++)
  {
    for (unsigned int i = 0; i < LIBMESH_DIM; i++)
      _centerpoints[grain](i) = _bottom_left(i) + _range(i) * MooseRandom::rand();
    if (_columnar_3D)
      _centerpoints[grain](2) = _bottom_left(2) + _range(2) * 0.5;
  }

  //Assign grains to specific order parameters in a way that maximizes the distance
  _assigned_op = PolycrystalICTools::assignPointsToVariables(_centerpoints, _op_num, _mesh, _var);
}

std::vector<float>
WorkerStemFit::compute_distances(std::vector<pcl::ModelCoefficients>  &cylinders)
{

    std::vector<float> distances ( _cloud->points.size () );
    std::fill ( distances.begin (), distances.end (), 0.5 );

    pcl::octree::OctreePointCloudSearch<PointI> octree ( 0.02f );
    octree.setInputCloud ( _cloud );
    octree.addPointsFromInputCloud ();
    for (size_t i = 0; i < cylinders.size(); i++) {

        pcl::ModelCoefficients cylinder = cylinders.at(i);
        std::vector<int> indices = indexOfPointsNearCylinder ( octree, cylinder );
        for ( size_t i = 0; i < indices.size (); i++ ) {
            PointI point = _cloud->points[indices[i]];
            simpleTree::Cylinder cyl (cylinder);

            float dist = cyl.distToPoint ( point );
            if ( std::abs ( dist ) < std::abs ( distances[indices[i]] ) ) {
                distances[indices[i]] = dist;
            }
        }
    }
    return distances;
}

std::pair<std::vector<count>, node> BFS::run_Feist(const Graph& g, node source) const {
    count infDist = std::numeric_limits<count>::max();
    count n = g.numberOfNodes();
    std::vector<count> distances(n, infDist);
    std::queue<node> q;

    distances[source] = 0;
    q.push(source);
    node max_node; 

    while (! q.empty()) {
        node current = q.front();
        q.pop();
        //std::cout << "current node in BFS: " << current << " ";

        // insert untouched neighbors into queue
        g.forNeighborsOf(current, [&](node neighbor) {
                if (distances[neighbor] == infDist) {
                    q.push(neighbor);
                    distances[neighbor] = distances[current] + 1;
                    max_node = neighbor; 
                }    
            });
    }

    return std::make_pair (distances, max_node);
}

template <typename PointT> double
pcl::MaximumLikelihoodSampleConsensus<PointT>::computeMedianAbsoluteDeviation (
    const PointCloudConstPtr &cloud, 
    const boost::shared_ptr <std::vector<int> > &indices, 
    double sigma)
{
  std::vector<double> distances (indices->size ());

  Eigen::Vector4f median;
  // median (dist (x - median (x)))
  computeMedian (cloud, indices, median);

  for (size_t i = 0; i < indices->size (); ++i)
  {
    pcl::Vector4fMapConst pt = cloud->points[(*indices)[i]].getVector4fMap ();
    Eigen::Vector4f ptdiff = pt - median;
    ptdiff[3] = 0;
    distances[i] = ptdiff.dot (ptdiff);
  }

  std::sort (distances.begin (), distances.end ());

  double result;
  size_t mid = indices->size () / 2;
  // Do we have a "middle" point or should we "estimate" one ?
  if (indices->size () % 2 == 0)
    result = (sqrt (distances[mid-1]) + sqrt (distances[mid])) / 2;
  else
    result = sqrt (distances[mid]);
  return (sigma * result);
}

 void KMeans<ScalarType, AssignmentType>::calculateInitGuess(const std::vector<Eigen::Matrix<ScalarType, Eigen::Dynamic, 1> >& data, std::vector<Eigen::Matrix<ScalarType, Eigen::Dynamic, 1> >& initGuess, unsigned int meanCount)
 {
     assert(meanCount > 0u);
     assert(data.size() > 0u);
     //first clear the initGuess vector. might not be empty.
     initGuess.clear();
     
     UniformRNG<double> rng;
     
     unsigned int dataSize = data.size();
     //insert first point.
     initGuess.push_back(data[std::rand() % dataSize]);
     
     Eigen::VectorXf distances(dataSize);
     
     float distance, minDistance;
     int minDistanceElement=0;
     double draw;
     
     //create meanCount guesses. first value has been taken.
     for (unsigned int g=1; g<meanCount; g++)
     {
         //calculate distances to nearest cluster mean guess
         for (unsigned int i=0; i<dataSize; i++)
         {
             distance = minDistance = std::numeric_limits<float>::max();
             for (unsigned int j=0; j<initGuess.size(); j++)
             {
                 // since we don't need the distance, but only the
                 // /smallest/ distance, we can omit the sqrt operation.
                 // it is not proven to be faster this way, so I will have
                 // both instructions here - you can choose. both work.
                 distance = (initGuess[j] - data[i]).norm();
                 //distance = (initGuess[j] - data[i]).array().square().sum();
                 if (distance < minDistance)
                 {
                     minDistance = distance;
                 }
             }
             distances[i] = minDistance;
         }
         //draw random value in [0, maxDistance];
         draw = rng.rand() * distances.maxCoeff();
         //find the element that best fits to the drawn value (distance).
         minDistance = std::numeric_limits<float>::max();
         for (unsigned int i=0; i<dataSize; i++)
         {
             distance = std::fabs(distances[i] - draw);
             if (distance < minDistance)
             {
                 minDistance = distance;
                 minDistanceElement = i;
             }
         }
         //take that element.
         initGuess.push_back(data[minDistanceElement]);
     }
     
     assert(initGuess.size() == meanCount);
 }

	bool Search(U_INT src, U_INT trg, T& PathRes, U_INT& Cost) {
		typedef boost::graph_traits<GraphT>::vertex_descriptor vertex_descriptor;
		std::vector<vertex_descriptor> predecessors(num_vertices(hGraph));
		if (src>=num_vertices(hGraph) || trg>=num_vertices(hGraph)) return false;
		vertex_descriptor source_vertex = vertex(src, hGraph);
		vertex_descriptor target_vertex = vertex(trg, hGraph);
		std::vector<U_INT> distances(num_vertices(hGraph));
		typedef std::vector<boost::default_color_type> colormap_t;
		colormap_t colors(num_vertices(hGraph));
		try {
			boost::astar_search(
			    hGraph, source_vertex,
			    distance_heuristic<GraphT>(hGraph, target_vertex),
			    boost::predecessor_map(&predecessors[0]).
			    weight_map(get(( &xEdge::cost ), hGraph)).
			    distance_map(&distances[0]).
			    color_map(&colors[0]).
			    visitor(astar_goal_visitor<vertex_descriptor>(target_vertex)));
		} catch (found_goal fg) {
			Cost=distances[target_vertex];
			PathRes.clear();
			PathRes.push_front(target_vertex);
			size_t max=num_vertices(hGraph);
			while (target_vertex != source_vertex) {
				if (target_vertex == predecessors[target_vertex])
					return false;
				target_vertex = predecessors[target_vertex];
				PathRes.push_front(target_vertex);
				if (!max--)
					return false;
			}
			return true;
		}
		return false;
	}

void toNormalizedNEXUS(ifstream & inf, ostream *os)
	{
	NxsTaxaBlock taxa;
	NxsTreesBlock trees(&taxa);
	NxsAssumptionsBlock assumptions(&taxa);
	NxsCharactersBlock character(&taxa, &assumptions);
	NxsDataBlock data(&taxa, &assumptions);
	NxsDistancesBlock distances(&taxa);
	NxsUnalignedBlock unaligned(&taxa, &assumptions);

	NormalizingReader nexus(os);
	nexus.Add(&taxa);
	nexus.Add(&trees);
	nexus.Add(&assumptions);
	nexus.Add(&character);
	nexus.Add(&data);
	nexus.Add(&distances);
	nexus.Add(&unaligned);

	if (os)
		{
		*os << "#NEXUS\n";
		}
	NormalizingToken token(inf, os);
	
	nexus.Execute(token);
	}

void computeVarianceAndCorrespondences(
		const pcl::PointCloud<pcl::PointXYZ>::ConstPtr & cloudA,
		const pcl::PointCloud<pcl::PointXYZ>::ConstPtr & cloudB,
		double maxCorrespondenceDistance,
		double & variance,
		int & correspondencesOut)
{
	variance = 1;
	correspondencesOut = 0;
	pcl::registration::CorrespondenceEstimation<pcl::PointXYZ, pcl::PointXYZ>::Ptr est;
	est.reset(new pcl::registration::CorrespondenceEstimation<pcl::PointXYZ, pcl::PointXYZ>);
	est->setInputTarget(cloudB);
	est->setInputSource(cloudA);
	pcl::Correspondences correspondences;
	est->determineCorrespondences(correspondences, maxCorrespondenceDistance);

	if(correspondences.size()>=3)
	{
		std::vector<double> distances(correspondences.size());
		for(unsigned int i=0; i<correspondences.size(); ++i)
		{
			distances[i] = correspondences[i].distance;
		}

		//variance
		std::sort(distances.begin (), distances.end ());
		double median_error_sqr = distances[distances.size () >> 1];
		variance = (2.1981 * median_error_sqr);
	}