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