102 lines
3.7 KiB
C++
102 lines
3.7 KiB
C++
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/*
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* Copyright (C) 2014 Open Source Robotics Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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#ifndef _GAZEBO_KMEANS_HH_
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#define _GAZEBO_KMEANS_HH_
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#include <vector>
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#include "gazebo/math/Vector3.hh"
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#include "gazebo/util/system.hh"
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namespace gazebo
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{
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namespace math
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{
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/// \addtogroup gazebo_math
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/// \{
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/// \class Kmeans Kmeans.hh math/gzmath.hh
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/// \brief K-Means clustering algorithm. Given a set of observations,
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/// k-means partitions the observations into k sets so as to minimize the
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/// within-cluster sum of squares.
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/// Description based on http://en.wikipedia.org/wiki/K-means_clustering.
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class GZ_MATH_VISIBLE Kmeans
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{
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/// \brief constructor
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/// \param[in] _obs Set of observations to cluster.
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public: Kmeans(const std::vector<Vector3> &_obs);
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/// \brief Destructor
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public: virtual ~Kmeans();
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/// \brief Get the observations to cluster.
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/// \return The vector of observations.
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public: std::vector<Vector3> Observations() const;
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/// \brief Set the observations to cluster.
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/// \param[in] _obs The new vector of observations.
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/// \return True if the vector is not empty or false otherwise.
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public: bool Observations(const std::vector<Vector3> &_obs);
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/// \brief Add observations to the cluster.
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/// \param[in] _obs Vector of observations.
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/// \return True if the _obs vector is not empty or false otherwise.
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public: bool AppendObservations(const std::vector<Vector3> &_obs);
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/// \brief Executes the k-means algorithm.
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/// \param[in] _k Number of partitions to cluster.
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/// \param[out] _centroids Vector of centroids. Each element contains the
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/// centroid of one cluster.
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/// \param[out] _labels Vector of labels. The size of this vector is
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/// equals to the number of observations. Each element represents the
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/// cluster to which observation belongs.
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/// \return True when the operation succeed or false otherwise. The
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/// operation will fail if the number of observations is not positive,
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/// if the number of clusters is non positive, or if the number of
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/// clusters if greater than the number of observations.
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public: bool Cluster(int _k,
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std::vector<Vector3> &_centroids,
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std::vector<unsigned int> &_labels);
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/// \brief Given an observation, it returns the closest centroid to it.
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/// \param[in] _p Point to check.
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/// \return The index of the closest centroid to the point _p.
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private: unsigned int ClosestCentroid(const Vector3 &_p) const;
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/// \brief Observations.
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private: std::vector<Vector3> obs;
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/// \brief Centroids.
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private: std::vector<Vector3> centroids;
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/// \brief Each element stores the cluster to which observation i belongs.
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private: std::vector<unsigned int> labels;
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/// \brief Used to calculate the centroid of each partition.
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private: std::vector<Vector3> sums;
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/// \brief Counts the number of observations contained in each partition.
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private: std::vector<unsigned int> counters;
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};
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/// \}
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}
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}
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#endif
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