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BrayCurtisDistance.cpp
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1 /*
2  * This program is free software; you can redistribute it and/or modify
3  * it under the terms of the GNU General Public License as published by
4  * the Free Software Foundation; either version 3 of the License, or
5  * (at your option) any later version.
6  *
7  * Written (W) 2008-2009 Christian Gehl
8  * Copyright (C) 2008-2009 Fraunhofer Institute FIRST
9  */
10 
11 #include <shogun/lib/config.h>
12 #include <shogun/lib/common.h>
13 #include <shogun/io/SGIO.h>
16 
17 using namespace shogun;
18 
21 {
22 }
23 
26 {
27  init(l, r);
28 }
29 
31 {
32  cleanup();
33 }
34 
35 bool CBrayCurtisDistance::init(CFeatures* l, CFeatures* r)
36 {
37  bool result=CDenseDistance<float64_t>::init(l,r);
38 
39  return result;
40 }
41 
43 {
44 }
45 
46 float64_t CBrayCurtisDistance::compute(int32_t idx_a, int32_t idx_b)
47 {
48  int32_t alen, blen;
49  bool afree, bfree;
50 
51  float64_t* avec=
52  ((CDenseFeatures<float64_t>*) lhs)->get_feature_vector(idx_a, alen, afree);
53  float64_t* bvec=
54  ((CDenseFeatures<float64_t>*) rhs)->get_feature_vector(idx_b, blen, bfree);
55 
56  ASSERT(alen==blen)
57 
58  float64_t s1=0;
59  float64_t s2=0;
60  {
61  for (int32_t i=0; i<alen; i++)
62  {
63  s1+=fabs(avec[i]-bvec[i]);
64  s2+=fabs(avec[i]+bvec[i]);
65  }
66  }
67 
68  ((CDenseFeatures<float64_t>*) lhs)->free_feature_vector(avec, idx_a, afree);
69  ((CDenseFeatures<float64_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree);
70 
71  // trap division by zero
72  if(s2==0)
73  return 0;
74 
75  return (s1/s2);
76 }

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