code/src/Algorithm/get_dissimilarities.c

   1 #include "Util/types.h"
   2 #include <stdlib.h>
   3 #include <math.h>
   4
   5 // compute L^p dissimilarities for a nxm matrix
   6 Real* get_dissimilarities_intra(Real* samples, uint32_t nbSamples, uint32_t nbValues, uint32_t p)
   7 {
   8     Real* dissimilarities = (Real*) malloc(nbSamples*nbSamples*sizeof(Real));
   9     for (uint32_t i=0; i<nbSamples; i++)
  10     {
  11         dissimilarities[i*nbSamples+i] = 0.0;
  12         for (uint32_t j=0; j<i; j++)
  13         {
  14             // dissimilarities[i*nbSamples+j] = L^p distance between reduced rows i and j
  15             double dissim = 0.0;
  16             for (uint32_t m=0; m<nbValues; m++)
  17             {
  18                 double delta = fabs(samples[i*nbValues+m] - samples[j*nbValues+m]);
  19                 dissim += pow(delta, p);
  20             }
  21             dissimilarities[i*nbSamples+j] = pow(dissim, 1.0/p);
  22             dissimilarities[j*nbSamples+i] = dissimilarities[i*nbSamples+j];
  23         }
  24     }
  25     return dissimilarities;
  26 }
  27
  28 // compute L^p dissimilarities between rows of 2 matrices
  29 Real* get_dissimilarities_inter(Real* mat1, uint32_t n1, Real* mat2, uint32_t n2,
  30     uint32_t nbValues, uint32_t p)
  31 {
  32     Real* dissimilarities = (Real*) malloc(n1*n2*sizeof(Real));
  33     for (uint32_t i=0; i<n1; i++)
  34     {
  35         for (uint32_t j=0; j<n2; j++)
  36         {
  37             double dissim = 0.0;
  38             for (uint32_t m=0; m<nbValues; m++)
  39             {
  40                 double delta = fabs(mat1[i*nbValues+m] - mat2[j*nbValues+m]);
  41                 dissim += pow(delta, p);
  42             }
  43             dissimilarities[i*n2+j] = pow(dissim, 1.0/p);
  44         }
  45     }
  46     return dissimilarities;
  47 }