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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>
17 
18 using namespace shogun;
19 
22 {
23 }
24 
27 {
28  init(l, r);
29 }
30 
32 {
33  cleanup();
34 }
35 
36 bool CBrayCurtisDistance::init(CFeatures* l, CFeatures* r)
37 {
38  bool result=CSimpleDistance<float64_t>::init(l,r);
39 
40  return result;
41 }
42 
44 {
45 }
46 
47 float64_t CBrayCurtisDistance::compute(int32_t idx_a, int32_t idx_b)
48 {
49  int32_t alen, blen;
50  bool afree, bfree;
51 
52  float64_t* avec=
53  ((CSimpleFeatures<float64_t>*) lhs)->get_feature_vector(idx_a, alen, afree);
54  float64_t* bvec=
55  ((CSimpleFeatures<float64_t>*) rhs)->get_feature_vector(idx_b, blen, bfree);
56 
57  ASSERT(alen==blen);
58 
59  float64_t s1=0;
60  float64_t s2=0;
61  {
62  for (int32_t i=0; i<alen; i++)
63  {
64  s1+=fabs(avec[i]-bvec[i]);
65  s2+=fabs(avec[i]+bvec[i]);
66  }
67  }
68 
69  ((CSimpleFeatures<float64_t>*) lhs)->free_feature_vector(avec, idx_a, afree);
70  ((CSimpleFeatures<float64_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree);
71 
72  // trap division by zero
73  if(s2==0)
74  return 0;
75 
76  return (s1/s2);
77 }

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