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() ;
}
}
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) ;
}