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00011 #include "lib/common.h"
00012 #include "kernel/GaussianShiftKernel.h"
00013 #include "features/Features.h"
00014 #include "features/SimpleFeatures.h"
00015 #include "lib/io.h"
00016
00017 using namespace shogun;
00018
00019 CGaussianShiftKernel::CGaussianShiftKernel(
00020 int32_t size, float64_t w, int32_t ms, int32_t ss)
00021 : CGaussianKernel(size, w), max_shift(ms), shift_step(ss)
00022 {
00023 }
00024
00025 CGaussianShiftKernel::CGaussianShiftKernel(
00026 CSimpleFeatures<float64_t>* l, CSimpleFeatures<float64_t>* r, float64_t w, int32_t ms, int32_t ss,
00027 int32_t size)
00028 : CGaussianKernel(l, r, w, size), max_shift(ms), shift_step(ss)
00029 {
00030 init(l,r);
00031 }
00032
00033 CGaussianShiftKernel::~CGaussianShiftKernel()
00034 {
00035 }
00036
00037 float64_t CGaussianShiftKernel::compute(int32_t idx_a, int32_t idx_b)
00038 {
00039 int32_t alen, blen;
00040 bool afree, bfree;
00041
00042 float64_t* avec=
00043 ((CSimpleFeatures<float64_t>*) lhs)->get_feature_vector(idx_a, alen, afree);
00044 float64_t* bvec=
00045 ((CSimpleFeatures<float64_t>*) rhs)->get_feature_vector(idx_b, blen, bfree);
00046 ASSERT(alen==blen);
00047
00048 float64_t result = 0.0 ;
00049 float64_t sum=0.0 ;
00050 for (int32_t i=0; i<alen; i++)
00051 sum+=(avec[i]-bvec[i])*(avec[i]-bvec[i]);
00052 result += exp(-sum/width) ;
00053
00054 for (int32_t shift = shift_step, s=1; shift<max_shift; shift+=shift_step, s++)
00055 {
00056 sum=0.0 ;
00057 for (int32_t i=0; i<alen-shift; i++)
00058 sum+=(avec[i+shift]-bvec[i])*(avec[i+shift]-bvec[i]);
00059 result += exp(-sum/width)/(2*s) ;
00060
00061 sum=0.0 ;
00062 for (int32_t i=0; i<alen-shift; i++)
00063 sum+=(avec[i]-bvec[i+shift])*(avec[i]-bvec[i+shift]);
00064 result += exp(-sum/width)/(2*s) ;
00065 }
00066
00067 ((CSimpleFeatures<float64_t>*) lhs)->free_feature_vector(avec, idx_a, afree);
00068 ((CSimpleFeatures<float64_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree);
00069
00070 return result;
00071 }