Neighbors

seqnum_neighbors

Signatures

UBIGINT[] seqnum_neighbors (seqnum UBIGINT, res INTEGER)
UBIGINT[] seqnum_neighbors (seqnum UBIGINT, res INTEGER, params STRUCT)

Description

Returns the sequential indices of all topologically adjacent cells. For hexagon grids, interior cells have 6 neighbors; pentagon cells (at icosahedron vertices) have 5. The result does not include the input cell itself.

The neighbor relationship is symmetric: if B is in seqnum_neighbors(A), then A is in seqnum_neighbors(B).

INFO

Not supported for TRIANGLE topology grids.

Example

SELECT seqnum_neighbors(2380::UBIGINT, 5);

┌──────────────────────────────────────────────────┐
│ seqnum_neighbors(CAST(2380 AS "UBIGINT"), 5)     │
│                   uint64[]                       │
├──────────────────────────────────────────────────┤
│ [2412, 2413, 2381, 2348, 2347, 2379]             │
└──────────────────────────────────────────────────┘

Vectorised usage

The function is fully vectorised -- use it over a table column:

SELECT seqnum, seqnum_neighbors(seqnum, 5) AS neighbors
FROM (VALUES (2380::UBIGINT), (2381::UBIGINT), (100::UBIGINT)) t(seqnum);