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00011 #include <shogun/lib/common.h>
00012 #include <shogun/kernel/GaussianShiftKernel.h>
00013 #include <shogun/features/Features.h>
00014 #include <shogun/io/SGIO.h>
00015
00016 using namespace shogun;
00017
00018 CGaussianShiftKernel::CGaussianShiftKernel()
00019 : CGaussianKernel(), max_shift(0), shift_step(0)
00020 {
00021 init();
00022 }
00023
00024 CGaussianShiftKernel::CGaussianShiftKernel(
00025 int32_t size, float64_t w, int32_t ms, int32_t ss)
00026 : CGaussianKernel(size, w), max_shift(ms), shift_step(ss)
00027 {
00028 init();
00029 }
00030
00031 CGaussianShiftKernel::CGaussianShiftKernel(
00032 CDenseFeatures<float64_t>* l, CDenseFeatures<float64_t>* r, float64_t w, int32_t ms, int32_t ss,
00033 int32_t size)
00034 : CGaussianKernel(l, r, w, size), max_shift(ms), shift_step(ss)
00035 {
00036 init();
00037 CGaussianKernel::init(l,r);
00038 }
00039
00040 CGaussianShiftKernel::~CGaussianShiftKernel()
00041 {
00042 }
00043
00044 float64_t CGaussianShiftKernel::compute(int32_t idx_a, int32_t idx_b)
00045 {
00046 int32_t alen, blen;
00047 bool afree, bfree;
00048
00049 float64_t* avec=
00050 ((CDenseFeatures<float64_t>*) lhs)->get_feature_vector(idx_a, alen, afree);
00051 float64_t* bvec=
00052 ((CDenseFeatures<float64_t>*) rhs)->get_feature_vector(idx_b, blen, bfree);
00053 ASSERT(alen==blen);
00054
00055 float64_t result = 0.0 ;
00056 float64_t sum=0.0 ;
00057 for (int32_t i=0; i<alen; i++)
00058 sum+=(avec[i]-bvec[i])*(avec[i]-bvec[i]);
00059 result += exp(-sum/width) ;
00060
00061 for (int32_t shift = shift_step, s=1; shift<max_shift; shift+=shift_step, s++)
00062 {
00063 sum=0.0 ;
00064 for (int32_t i=0; i<alen-shift; i++)
00065 sum+=(avec[i+shift]-bvec[i])*(avec[i+shift]-bvec[i]);
00066 result += exp(-sum/width)/(2*s) ;
00067
00068 sum=0.0 ;
00069 for (int32_t i=0; i<alen-shift; i++)
00070 sum+=(avec[i]-bvec[i+shift])*(avec[i]-bvec[i+shift]);
00071 result += exp(-sum/width)/(2*s) ;
00072 }
00073
00074 ((CDenseFeatures<float64_t>*) lhs)->free_feature_vector(avec, idx_a, afree);
00075 ((CDenseFeatures<float64_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree);
00076
00077 return result;
00078 }
00079
00080 void CGaussianShiftKernel::init()
00081 {
00082 SG_ADD(&max_shift, "max_shift", "Maximum shift.", MS_AVAILABLE);
00083 SG_ADD(&shift_step, "shift_step", "Shift stepsize.", MS_AVAILABLE);
00084 }
00085