index_heap.h

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/*

Copyright (c) 2010--2011, Stephane Magnenat, ASL, ETHZ, Switzerland
You can contact the author at <stephane at magnenat dot net>

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      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

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*/

#ifndef __INDEX_HEAP_H
#define __INDEX_HEAP_H

#include "nabo.h"
#include <vector>
#include <algorithm>
#include <limits>
#include <iostream>

namespace Nabo
{

        template<typename IT, typename VT>
        struct IndexHeapSTL
        {
                typedef IT Index;
                typedef VT Value;
                
                struct Entry
                {
                        IT index; 
                        VT value; 
                        
                        Entry(const IT index, const VT value): index(index), value(value) {}
                        friend bool operator<(const Entry& e0, const Entry& e1) { return e0.value < e1.value; }
                };
                typedef std::vector<Entry> Entries;
                typedef typename Eigen::Matrix<Index, Eigen::Dynamic, 1> IndexVector;
                typedef typename Eigen::Matrix<Value, Eigen::Dynamic, 1> ValueVector;
                
                Entries data;
                const size_t nbNeighbours;

                

                IndexHeapSTL(const size_t size):
                        data(1, Entry(0, std::numeric_limits<VT>::infinity())),
                        nbNeighbours(size)
                {
                        data.reserve(size);
                }
                
                inline void reset()
                {
                        data.clear();
                        data.push_back(Entry(0, std::numeric_limits<VT>::infinity()));
                }
                

                inline const VT& headValue() const { return data.front().value; }
                

                inline void replaceHead(const Index index, const Value value)
                {

                        if (data.size() == nbNeighbours)
                        {       // we have enough neighbours to discard largest
                                pop_heap(data.begin(), data.end());
                                data.back() = Entry(index, value);
                        }
                        else
                        {       // missing neighbours
                                data.push_back(Entry(index, value));
                        }
                        // ensure heap
                        push_heap(data.begin(), data.end());
                }
                
                inline void sort()
                {
                        sort_heap (data.begin(), data.end());
                }
                

                template<typename DI, typename DV>
                inline void getData(const Eigen::MatrixBase<DI>& indices, const Eigen::MatrixBase<DV> & values) const
                {
                        // note: we must implement this hack because of problem with reference to temporary
                        // C++0x will solve this with rvalue
                        // see: http://eigen.tuxfamily.org/dox-devel/TopicFunctionTakingEigenTypes.html
                        // for more informations
                        size_t i = 0;
                        for (; i < data.size(); ++i)
                        {
                                const_cast<Eigen::MatrixBase<DI>&>(indices).coeffRef(i) = data[i].index;
                                const_cast<Eigen::MatrixBase<DV>&>(values).coeffRef(i) = data[i].value;
                        }
                        for (; i < nbNeighbours; ++i)
                        {
                                const_cast<Eigen::MatrixBase<DI>&>(indices).coeffRef(i) = 0;
                                const_cast<Eigen::MatrixBase<DV>&>(values).coeffRef(i) = std::numeric_limits<VT>::infinity();
                        }
                }
                
#if 0


                inline IndexVector getIndexes() const
                {
                        IndexVector indexes(data.capacity());
                        size_t i = 0;
                        for (; i < data.size(); ++i)
                                indexes.coeffRef(i) = data[i].index;
                        for (; i < data.capacity(); ++i)
                                indexes.coeffRef(i) = 0;
                        return indexes;
                }
#endif
        };
        
#if 0


        template<typename IT, typename VT>
        struct IndexHeapBruteForceVector
        {
                typedef IT Index;
                typedef VT Value;
                
                struct Entry
                {
                        IT index; 
                        VT value;  
                        
                        Entry(const IT index, const VT value): index(index), value(value) {} 
                        friend bool operator<(const Entry& e0, const Entry& e1) { return e0.value < e1.value; }
                };
                typedef std::vector<Entry> Entries;
                typedef typename Eigen::Matrix<Index, Eigen::Dynamic, 1> IndexVector;
                
                Entries data;
                const VT& headValueRef;
                const size_t sizeMinusOne;
                

                IndexHeapBruteForceVector(const size_t size):
                        data(size, Entry(0, std::numeric_limits<VT>::infinity())),
                        headValueRef((data.end() - 1)->value),
                        sizeMinusOne(data.size() - 1)
                {
                }
                
                inline void reset()
                {
                        for (typename Entries::iterator it(data.begin()); it != data.end(); ++it)
                        {
                                it->value = std::numeric_limits<VT>::infinity();
                                it->index = 0;
                        }
                }
                

                inline const VT& headValue() const { return data[0].value; }
                

                inline void replaceHead(const Index index, const Value value)
                {
                        register size_t i = 0;
                        for (; i < sizeMinusOne; ++i)
                        {
                                if (data[i + 1].value > value)
                                        data[i] = data[i + 1];
                                else
                                        break;
                        }
                        data[i].value = value;
                        data[i].index = index;
                }
                
                inline void sort()
                {
                        // no need to sort as data are already sorted
                }
                

                inline IndexVector getIndexes() const
                {
                        IndexVector indexes(data.size());
                        for (size_t i = 0; i < data.size(); ++i)
                                indexes.coeffRef(i) = data[sizeMinusOne-i].index;
                        return indexes;
                }
        };
#endif
        

        template<typename IT, typename VT>
        struct IndexHeapBruteForceVector
        {
                typedef IT Index;
                typedef VT Value;
                
                struct Entry
                {
                        IT index; 
                        VT value;  
                        
                        Entry(const IT index, const VT value): index(index), value(value) {} 
                        friend bool operator<(const Entry& e0, const Entry& e1) { return e0.value < e1.value; }
                };
                typedef std::vector<Entry> Entries;
                typedef typename Eigen::Matrix<Index, Eigen::Dynamic, 1> IndexVector;
                typedef typename Eigen::Matrix<Value, Eigen::Dynamic, 1> ValueVector;
                
                Entries data;
                const VT& headValueRef;
                const size_t sizeMinusOne;
                

                IndexHeapBruteForceVector(const size_t size):
                data(size, Entry(0, std::numeric_limits<VT>::infinity())),
                headValueRef((data.end() - 1)->value),
                sizeMinusOne(data.size() - 1)
                {
                }
                
                inline void reset()
                {
                        for (typename Entries::iterator it(data.begin()); it != data.end(); ++it)
                        {
                                it->value = std::numeric_limits<VT>::infinity();
                                it->index = 0;
                        }
                }
                

                inline const VT& headValue() const { return headValueRef; }
                

                inline void replaceHead(const Index index, const Value value)
                {
                        register size_t i;
                        for (i = sizeMinusOne; i > 0; --i)
                        {
                                if (data[i-1].value > value)
                                        data[i] = data[i-1];
                                else
                                        break;
                        }
                        data[i].value = value;
                        data[i].index = index;
                }
                
                inline void sort()
                {
                        // no need to sort as data are already sorted
                }
                

                template<typename DI, typename DV>
                inline void getData(const Eigen::MatrixBase<DI>& indices, const Eigen::MatrixBase<DV> & values) const
                {
                        // note: we must implement this hack because of problem with reference to temporary
                        // C++0x will solve this with rvalue
                        // see: http://eigen.tuxfamily.org/dox-devel/TopicFunctionTakingEigenTypes.html
                        // for more informations
                        for (size_t i = 0; i < data.size(); ++i)
                        {
                                const_cast<Eigen::MatrixBase<DI>&>(indices).coeffRef(i) = data[i].index;
                                const_cast<Eigen::MatrixBase<DV>&>(values).coeffRef(i) = data[i].value;
                        }
                }
#if 0


                inline IndexVector getIndexes() const
                {
                        IndexVector indexes(data.size());
                        for (size_t i = 0; i < data.size(); ++i)
                                indexes.coeffRef(i) = data[i].index;
                        return indexes;
                }
#endif
        };
}

#endif // __INDEX_HEAP_H