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