PostGIS  2.2.7dev-r@@SVN_REVISION@@
int cluster_within_distance ( LWGEOM **  geoms,
uint32_t  num_geoms,
double  tolerance,
LWGEOM ***  clusterGeoms,
uint32_t *  num_clusters 
)

Takes an array of LWGEOM* and constructs an array of LWGEOM*, where each element in the constructed array is a GeometryCollection representing a set of geometries separated by no more than the specified tolerance.

Caller is responsible for freeing the input array, but not the LWGEOM* items inside it.

Definition at line 317 of file lwgeom_geos_cluster.c.

References combine_geometries(), LW_FAILURE, UnionIfDWithinContext::uf, UF_create(), UF_destroy(), and union_pairs_within_distance().

Referenced by cluster_within_distance_garray(), and perform_cluster_within_distance_test().

318 {
319  int cluster_success;
320  UNIONFIND* uf = UF_create(num_geoms);
321 
322  if (union_pairs_within_distance(geoms, num_geoms, uf, tolerance) == LW_FAILURE)
323  {
324  UF_destroy(uf);
325  return LW_FAILURE;
326  }
327 
328  cluster_success = combine_geometries(uf, (void**) geoms, num_geoms, (void***) clusterGeoms, num_clusters, 1);
329  UF_destroy(uf);
330  return cluster_success;
331 }
void UF_destroy(UNIONFIND *uf)
Definition: lwunionfind.c:40
#define LW_FAILURE
Definition: liblwgeom.h:64
UNIONFIND * UF_create(uint32_t N)
Definition: lwunionfind.c:21
static int union_pairs_within_distance(LWGEOM **geoms, uint32_t num_geoms, UNIONFIND *uf, double tolerance)
static int combine_geometries(UNIONFIND *uf, void **geoms, uint32_t num_geoms, void ***clustersGeoms, uint32_t *num_clusters, char is_lwgeom)
Uses a UNIONFIND to identify the set with which each input geometry is associated, and groups the geometries into GeometryCollections.

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