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TanimotoKernelNormalizer.h
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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 Soeren Sonnenburg
8  * Copyright (C) 2008-2009 Fraunhofer Institute FIRST and Max-Planck-Society
9  */
10 
11 #ifndef _TANIMOTOKERNELNORMALIZER_H___
12 #define _TANIMOTOKERNELNORMALIZER_H___
13 
16 
17 namespace shogun
18 {
27 {
28  public:
33  CTanimotoKernelNormalizer(bool use_opt_diag=false)
34  : CKernelNormalizer(), diag_lhs(NULL), diag_rhs(NULL),
36  {
37  }
38 
41  {
42  SG_FREE(diag_lhs);
43  SG_FREE(diag_rhs);
44  }
45 
48  virtual bool init(CKernel* k)
49  {
50  ASSERT(k)
51  int32_t num_lhs=k->get_num_vec_lhs();
52  int32_t num_rhs=k->get_num_vec_rhs();
53  ASSERT(num_lhs>0)
54  ASSERT(num_rhs>0)
55 
56  CFeatures* old_lhs=k->lhs;
57  CFeatures* old_rhs=k->rhs;
58 
59  k->lhs=old_lhs;
60  k->rhs=old_lhs;
61  bool r1=alloc_and_compute_diag(k, diag_lhs, num_lhs);
62 
63  k->lhs=old_rhs;
64  k->rhs=old_rhs;
65  bool r2=alloc_and_compute_diag(k, diag_rhs, num_rhs);
66 
67  k->lhs=old_lhs;
68  k->rhs=old_rhs;
69 
70  return r1 && r2;
71  }
72 
79  float64_t value, int32_t idx_lhs, int32_t idx_rhs)
80  {
81  float64_t diag_sum=diag_lhs[idx_lhs]*diag_rhs[idx_rhs];
82  return value/(diag_sum-value);
83  }
84 
89  virtual float64_t normalize_lhs(float64_t value, int32_t idx_lhs)
90  {
91  SG_ERROR("linadd not supported with Tanimoto normalization.\n")
92  return 0;
93  }
94 
99  virtual float64_t normalize_rhs(float64_t value, int32_t idx_rhs)
100  {
101  SG_ERROR("linadd not supported with Tanimoto normalization.\n")
102  return 0;
103  }
104 
110  virtual const char* get_name() const {
111  return "TanimotoKernelNormalizer"; }
112 
113  public:
118  bool alloc_and_compute_diag(CKernel* k, float64_t* &v, int32_t num)
119  {
120  SG_FREE(v);
121  v=SG_MALLOC(float64_t, num);
122 
123  for (int32_t i=0; i<num; i++)
124  {
125  if (k->get_kernel_type() == K_COMMWORDSTRING)
126  {
128  v[i]=((CCommWordStringKernel*) k)->compute_diag(i);
129  else
130  v[i]=((CCommWordStringKernel*) k)->compute_helper(i,i, true);
131  }
132  else
133  v[i]=k->compute(i,i);
134 
135  if (v[i]==0.0)
136  v[i]=1e-16; /* avoid divide by zero exception */
137  }
138 
139  return (v!=NULL);
140  }
141 
142  protected:
149 };
150 }
151 #endif

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