core.pairs (procNode)

Every pair of points within a radius: for each query point, the source points that stand within the radius of it, as a list of owners and items.

Built from core.spatial over the sources, the hash_count and hash_gather kernels, scan of the counts and expand of each query's list into one row per pair. Outputs: owner (the query point of each pair), items (the source point of each pair), counts and offsets (each query's list in items) and total. A point is not its own neighbour when the queries are the sources.

Inputs

• points (Geometry). The query points.
• sources (Geometry, optional). The points looked at. Left empty, the query points look at each other.
• radius (Number). Default 1.0. Above 0. How far a query point reaches.

Outputs

• owner: the query point of each pair.
• items: the source point of each pair.
• counts: the length of each query's list.
• offsets: where each query's list starts in items.
• total: the number of pairs.
• spatial: the core.spatial record the sources were indexed by.

Example

local points = g.points.grid({ countX = 4, countZ = 1, spacing = 1 })
local pairs = g.core.pairs({ points = points, radius = 1.5 })

Six pairs: each point with the points 1 apart on either side of it.