PostGIS  3.1.6dev-r@@SVN_REVISION@@

◆ test_kmeans()

static void test_kmeans ( void  )
static

Definition at line 1709 of file cu_algorithm.c.

1710 {
1711  static int cluster_size = 100;
1712  static int num_clusters = 4;
1713  static double spread = 1.5;
1714  int N = cluster_size * num_clusters;
1715  LWGEOM **geoms;
1716  int i, j, k=0;
1717  int *r;
1718 
1719  geoms = lwalloc(sizeof(LWGEOM*) * N);
1720 
1721  for (j = 0; j < num_clusters; j++) {
1722  for (i = 0; i < cluster_size; i++)
1723  {
1724  double u1 = 1.0 * rand() / RAND_MAX;
1725  double u2 = 1.0 * rand() / RAND_MAX;
1726  double z1 = spread * j + sqrt(-2*log2(u1))*cos(2*M_PI*u2);
1727  double z2 = spread * j + sqrt(-2*log2(u1))*sin(2*M_PI*u2);
1728 
1729  LWPOINT *lwp = lwpoint_make2d(SRID_UNKNOWN, z1, z2);
1730  geoms[k++] = lwpoint_as_lwgeom(lwp);
1731  }
1732  }
1733 
1734  r = lwgeom_cluster_kmeans((const LWGEOM **)geoms, N, num_clusters);
1735 
1736  // for (i = 0; i < k; i++)
1737  // {
1738  // printf("[%d] %s\n", r[i], lwgeom_to_ewkt(geoms[i]));
1739  // }
1740 
1741  /* Clean up */
1742  lwfree(r);
1743  for (i = 0; i < k; i++)
1744  lwgeom_free(geoms[i]);
1745  lwfree(geoms);
1746 
1747  return;
1748 }
char * r
Definition: cu_in_wkt.c:24
LWPOINT * lwpoint_make2d(int32_t srid, double x, double y)
Definition: lwpoint.c:163
void lwgeom_free(LWGEOM *geom)
Definition: lwgeom.c:1138
int * lwgeom_cluster_kmeans(const LWGEOM **geoms, uint32_t ngeoms, uint32_t k)
Take a list of LWGEOMs and a number of clusters and return an integer array indicating which cluster ...
Definition: lwkmeans.c:206
void lwfree(void *mem)
Definition: lwutil.c:242
LWGEOM * lwpoint_as_lwgeom(const LWPOINT *obj)
Definition: lwgeom.c:327
void * lwalloc(size_t size)
Definition: lwutil.c:227
#define SRID_UNKNOWN
Unknown SRID value.
Definition: liblwgeom.h:229

References lwalloc(), lwfree(), lwgeom_cluster_kmeans(), lwgeom_free(), lwpoint_as_lwgeom(), lwpoint_make2d(), r, and SRID_UNKNOWN.

Referenced by algorithms_suite_setup().

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