SparseGaussianKernel.cpp

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00001 /*
00002  * This program is free software; you can redistribute it and/or modify
00003  * it under the terms of the GNU General Public License as published by
00004  * the Free Software Foundation; either version 3 of the License, or
00005  * (at your option) any later version.
00006  *
00007  * Written (W) 1999-2009 Soeren Sonnenburg
00008  * Copyright (C) 1999-2009 Fraunhofer Institute FIRST and Max-Planck-Society
00009  */
00010 
00011 #include "lib/common.h"
00012 #include "lib/io.h"
00013 #include "kernel/SparseGaussianKernel.h"
00014 #include "features/Features.h"
00015 #include "features/SparseFeatures.h"
00016 
00017 using namespace shogun;
00018 
00019 CSparseGaussianKernel::CSparseGaussianKernel(int32_t size, float64_t w)
00020 : CSparseKernel<float64_t>(size), width(w), sq_lhs(NULL), sq_rhs(NULL)
00021 {
00022 }
00023 
00024 CSparseGaussianKernel::CSparseGaussianKernel(
00025     CSparseFeatures<float64_t>* l, CSparseFeatures<float64_t>* r, float64_t w)
00026 : CSparseKernel<float64_t>(10), width(w), sq_lhs(NULL), sq_rhs(NULL)
00027 {
00028     init(l, r);
00029 }
00030 
00031 CSparseGaussianKernel::~CSparseGaussianKernel()
00032 {
00033     cleanup();
00034 }
00035 
00036 bool CSparseGaussianKernel::init(CFeatures* l, CFeatures* r)
00037 {
00039     cleanup();
00040 
00041     CSparseKernel<float64_t>::init(l, r);
00042 
00043     sq_lhs=new float64_t[lhs->get_num_vectors()];
00044     sq_lhs=((CSparseFeatures<float64_t>*) lhs)->compute_squared(sq_lhs);
00045     if (lhs==rhs)
00046         sq_rhs=sq_lhs;
00047     else
00048     {
00049         sq_rhs=new float64_t[rhs->get_num_vectors()];
00050         sq_rhs=((CSparseFeatures<float64_t>*) rhs)->compute_squared(sq_rhs);
00051     }
00052 
00053     return init_normalizer();
00054 }
00055 
00056 void CSparseGaussianKernel::cleanup()
00057 {
00058     if (sq_lhs != sq_rhs)
00059         delete[] sq_rhs;
00060     sq_rhs = NULL;
00061 
00062     delete[] sq_lhs;
00063     sq_lhs = NULL;
00064 
00065     CKernel::cleanup();
00066 }
00067 
00068 float64_t CSparseGaussianKernel::compute(int32_t idx_a, int32_t idx_b)
00069 {
00070     //float64_t result = sq_lhs[idx_a] + sq_rhs[idx_b];
00071     float64_t result=((CSparseFeatures<float64_t>*) lhs)->compute_squared_norm(
00072         (CSparseFeatures<float64_t>*) lhs, sq_lhs, idx_a,
00073         (CSparseFeatures<float64_t>*) rhs, sq_rhs, idx_b);
00074     return exp(-result/width);
00075 }

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