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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/features/SimpleFeatures.h>
00015 #include <shogun/io/SGIO.h>
00016
00017 using namespace shogun;
00018
00019 CGaussianShiftKernel::CGaussianShiftKernel()
00020 : CGaussianKernel(), max_shift(0), shift_step(0)
00021 {
00022 init();
00023 }
00024
00025 CGaussianShiftKernel::CGaussianShiftKernel(
00026 int32_t size, float64_t w, int32_t ms, int32_t ss)
00027 : CGaussianKernel(size, w), max_shift(ms), shift_step(ss)
00028 {
00029 init();
00030 }
00031
00032 CGaussianShiftKernel::CGaussianShiftKernel(
00033 CSimpleFeatures<float64_t>* l, CSimpleFeatures<float64_t>* r, float64_t w, int32_t ms, int32_t ss,
00034 int32_t size)
00035 : CGaussianKernel(l, r, w, size), max_shift(ms), shift_step(ss)
00036 {
00037 init();
00038 CGaussianKernel::init(l,r);
00039 }
00040
00041 CGaussianShiftKernel::~CGaussianShiftKernel()
00042 {
00043 }
00044
00045 float64_t CGaussianShiftKernel::compute(int32_t idx_a, int32_t idx_b)
00046 {
00047 int32_t alen, blen;
00048 bool afree, bfree;
00049
00050 float64_t* avec=
00051 ((CSimpleFeatures<float64_t>*) lhs)->get_feature_vector(idx_a, alen, afree);
00052 float64_t* bvec=
00053 ((CSimpleFeatures<float64_t>*) rhs)->get_feature_vector(idx_b, blen, bfree);
00054 ASSERT(alen==blen);
00055
00056 float64_t result = 0.0 ;
00057 float64_t sum=0.0 ;
00058 for (int32_t i=0; i<alen; i++)
00059 sum+=(avec[i]-bvec[i])*(avec[i]-bvec[i]);
00060 result += exp(-sum/width) ;
00061
00062 for (int32_t shift = shift_step, s=1; shift<max_shift; shift+=shift_step, s++)
00063 {
00064 sum=0.0 ;
00065 for (int32_t i=0; i<alen-shift; i++)
00066 sum+=(avec[i+shift]-bvec[i])*(avec[i+shift]-bvec[i]);
00067 result += exp(-sum/width)/(2*s) ;
00068
00069 sum=0.0 ;
00070 for (int32_t i=0; i<alen-shift; i++)
00071 sum+=(avec[i]-bvec[i+shift])*(avec[i]-bvec[i+shift]);
00072 result += exp(-sum/width)/(2*s) ;
00073 }
00074
00075 ((CSimpleFeatures<float64_t>*) lhs)->free_feature_vector(avec, idx_a, afree);
00076 ((CSimpleFeatures<float64_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree);
00077
00078 return result;
00079 }
00080
00081 void CGaussianShiftKernel::init()
00082 {
00083 m_parameters->add(&max_shift, "max_shift", "Maximum shift.");
00084 m_parameters->add(&shift_step, "shift_step", "Shift stepsize.");
00085 }
00086