ManhattanWordDistance.cpp
Go to the documentation of this file.00001
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00012 #include "lib/common.h"
00013 #include "distance/ManhattanWordDistance.h"
00014 #include "features/Features.h"
00015 #include "features/StringFeatures.h"
00016 #include "lib/io.h"
00017
00018 using namespace shogun;
00019
00020 CManhattanWordDistance::CManhattanWordDistance()
00021 : CStringDistance<uint16_t>()
00022 {
00023 SG_DEBUG("CManhattanWordDistance created");
00024 dictionary_size= 1<<(sizeof(uint16_t)*8);
00025 dictionary_weights = new float64_t[dictionary_size];
00026 SG_DEBUG( "using dictionary of %d bytes\n", dictionary_size);
00027 }
00028
00029 CManhattanWordDistance::CManhattanWordDistance(
00030 CStringFeatures<uint16_t>* l, CStringFeatures<uint16_t>* r)
00031 : CStringDistance<uint16_t>()
00032 {
00033 SG_DEBUG("CManhattanWordDistance created");
00034 dictionary_size= 1<<(sizeof(uint16_t)*8);
00035 dictionary_weights = new float64_t[dictionary_size];
00036 SG_DEBUG( "using dictionary of %d bytes\n", dictionary_size);
00037
00038 init(l, r);
00039 }
00040
00041 CManhattanWordDistance::~CManhattanWordDistance()
00042 {
00043 cleanup();
00044
00045 delete[] dictionary_weights;
00046 }
00047
00048 bool CManhattanWordDistance::init(CFeatures* l, CFeatures* r)
00049 {
00050 bool result=CStringDistance<uint16_t>::init(l,r);
00051 return result;
00052 }
00053
00054 void CManhattanWordDistance::cleanup()
00055 {
00056 }
00057
00058 float64_t CManhattanWordDistance::compute(int32_t idx_a, int32_t idx_b)
00059 {
00060 int32_t alen, blen;
00061 bool free_avec, free_bvec;
00062
00063 uint16_t* avec=((CStringFeatures<uint16_t>*) lhs)->
00064 get_feature_vector(idx_a, alen, free_avec);
00065 uint16_t* bvec=((CStringFeatures<uint16_t>*) rhs)->
00066 get_feature_vector(idx_b, blen, free_bvec);
00067
00068 int32_t result=0;
00069
00070 int32_t left_idx=0;
00071 int32_t right_idx=0;
00072
00073 while (left_idx < alen && right_idx < blen)
00074 {
00075 uint16_t sym=avec[left_idx];
00076 if (avec[left_idx]==bvec[right_idx])
00077 {
00078 int32_t old_left_idx=left_idx;
00079 int32_t old_right_idx=right_idx;
00080
00081 while (left_idx< alen && avec[left_idx]==sym)
00082 left_idx++;
00083
00084 while (right_idx< blen && bvec[right_idx]==sym)
00085 right_idx++;
00086
00087 result += CMath::abs( (left_idx-old_left_idx) - (right_idx-old_right_idx) );
00088 }
00089 else if (avec[left_idx]<bvec[right_idx])
00090 {
00091
00092 while (left_idx< alen && avec[left_idx]==sym)
00093 {
00094 result++;
00095 left_idx++;
00096 }
00097 }
00098 else
00099 {
00100 sym=bvec[right_idx];
00101
00102 while (right_idx< blen && bvec[right_idx]==sym)
00103 {
00104 result++;
00105 right_idx++;
00106 }
00107 }
00108 }
00109
00110 result+=blen-right_idx + alen-left_idx;
00111
00112 ((CStringFeatures<uint16_t>*) lhs)->
00113 free_feature_vector(avec, idx_a, free_avec);
00114 ((CStringFeatures<uint16_t>*) rhs)->
00115 free_feature_vector(bvec, idx_b, free_bvec);
00116
00117 return result;
00118 }
00119