96 lines
2.4 KiB
C++
96 lines
2.4 KiB
C++
// Copyright (c) 2018 GeometryFactory Sarl (France).
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// All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org).
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//
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// $URL$
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// $Id$
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// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
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//
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// Author(s) : Simon Giraudot
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#ifndef CGAL_CLASSIFICATION_FEATURE_CLUSTER_VARIANCE_FEATURE_H
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#define CGAL_CLASSIFICATION_FEATURE_CLUSTER_VARIANCE_FEATURE_H
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#include <CGAL/license/Classification.h>
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#include <vector>
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#include <sstream>
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#include <CGAL/Classification/Feature_base.h>
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namespace CGAL {
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namespace Classification {
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namespace Feature {
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/*!
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\ingroup PkgClassificationCluster
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\brief %Feature that computes the variance values of an itemwise
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feature over the respective items of clusters.
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Its default name is "variance_" + the name of the itemwise feature.
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*/
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class Cluster_variance_of_feature : public CGAL::Classification::Feature_base
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{
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std::vector<float> m_values;
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public:
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/*!
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\brief constructs the feature.
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\tparam ClusterRange model of `ConstRange`. Its iterator type
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is `RandomAccessIterator` and its value type is the key type of
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`Cluster`.
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\param clusters input range.
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\param itemwise_feature feature that takes values on the range of
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items from which `clusters` is a subset.
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\param mean_feature `Cluster_mean_of_feature` computed on
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`itemwise_feature`.
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*/
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template <typename ClusterRange>
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Cluster_variance_of_feature (ClusterRange& clusters,
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Feature_handle itemwise_feature,
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Feature_handle mean_feature)
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{
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std::ostringstream oss;
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oss << "variance_" << itemwise_feature->name();
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this->set_name (oss.str());
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m_values.reserve (clusters.size());
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for (std::size_t i = 0; i < clusters.size(); ++ i)
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{
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double mean = double (mean_feature->value(i));
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double variance = 0.;
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for (std::size_t j = 0; j < clusters[i].size(); ++ j)
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{
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double v = double (itemwise_feature->value (clusters[i].index(j)));
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variance += (v - mean) * (v - mean);
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}
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variance /= clusters[i].size();
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m_values.push_back (float(variance));
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}
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}
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/// \cond SKIP_IN_MANUAL
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virtual float value (std::size_t cluster_index)
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{
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return m_values[cluster_index];
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}
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/// \endcond
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};
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} // namespace Feature
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} // namespace Classification
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} // namespace CGAL
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#endif // CGAL_CLASSIFICATION_FEATURE_CLUSTER_VARIANCE_FEATURE_H
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