Exemple #1
0
void
init_data (vl_size numDimensions, vl_size numSamples, float ** X, float ** Y)
{
  int i ;
  float * Xi = *X = vl_malloc(sizeof(float) * numDimensions * numSamples) ;
  float * Yi = *Y = vl_malloc(sizeof(float) * numDimensions * numSamples) ;
  for (i = 0 ; i < numDimensions * numSamples ; ++ i) {
    *Xi++ = vl_rand_real1() ;
    *Yi++ = vl_rand_real1() ;
  }
}
Exemple #2
0
static void
VL_XCAT(_vl_kmeans_seed_centers_plus_plus_, SFX)
(VlKMeans * self,
 TYPE const * data,
 vl_size dimension,
 vl_size numData,
 vl_size numCenters)
{
  vl_uindex x, c ;
  VlRand * rand = vl_get_rand () ;
  TYPE * distances = vl_malloc (sizeof(TYPE) * numData) ;
  TYPE * minDistances = vl_malloc (sizeof(TYPE) * numData) ;
#if (FLT == VL_TYPE_FLOAT)
  VlFloatVectorComparisonFunction distFn = vl_get_vector_comparison_function_f(self->distance) ;
#else
  VlDoubleVectorComparisonFunction distFn = vl_get_vector_comparison_function_d(self->distance) ;
#endif

  self->dimension = dimension ;
  self->numCenters = numCenters ;
  self->centers = vl_malloc (sizeof(TYPE) * dimension * numCenters) ;

  for (x = 0 ; x < numData ; ++x) {
    minDistances[x] = (TYPE) VL_INFINITY_D ;
  }

  /* select the first point at random */
  x = vl_rand_uindex (rand, numData) ;
  c = 0 ;
  while (1) {
    TYPE energy = 0 ;
    TYPE acc = 0 ;
    TYPE thresh = (TYPE) vl_rand_real1 (rand) ;

    memcpy ((TYPE*)self->centers + c * dimension,
            data + x * dimension,
            sizeof(TYPE) * dimension) ;

    c ++ ;
    if (c == numCenters) break ;

    VL_XCAT(vl_eval_vector_comparison_on_all_pairs_, SFX)
    (distances,
     dimension,
     (TYPE*)self->centers + (c - 1) * dimension, 1,
     data, numData,
     distFn) ;

    for (x = 0 ; x < numData ; ++x) {
      minDistances[x] = VL_MIN(minDistances[x], distances[x]) ;
      energy += minDistances[x] ;
    }

    for (x = 0 ; x < numData - 1 ; ++x) {
      acc += minDistances[x] ;
      if (acc >= thresh * energy) break ;
    }
  }

  vl_free(distances) ;
  vl_free(minDistances) ;
}