a5_covering_predicates: Test coverings

In a5R: 'A5' Discrete Global Grid System

Test coverings

Description

a5_contains() tests whether each cell is in a covering, and a5_overlaps() whether two coverings share any cell. Both work on the compacted cells, without expanding them, and element by element, recycling a length-one argument.

Usage

a5_contains(x, cell)

a5_overlaps(x, y)

Arguments

x	An a5_covering vector, or an object as_a5_covering() accepts.
cell	An a5_cell vector, each at the resolution of its covering.
y	An a5_covering vector, at the same resolution as x.

Details

a5_contains() is a point-in-polygon test once the point is indexed at the covering's resolution: a5_contains(covering, a5_lonlat_to_cell(lon, lat, a5_covering_resolution(covering))). The cell must be at the covering's resolution, or it is an error: A5 cells do not nest geometrically, so a finer cell is not guaranteed to lie inside the coarser cell that holds it in the index. An empty covering contains no cell.

Value

A logical vector of the common size of the inputs. NA where either input is NA.

See Also

a5_set_operations.

Examples

poly <- wk::wkt("POLYGON ((-3.4 55.85, -3 55.85, -3 56.05, -3.4 56.05, -3.4 55.85))")
edinburgh <- a5_polygon_to_cells(poly, resolution = 12)

# point in polygon, at the covering's resolution
points <- a5_lonlat_to_cell(c(-3.19, -4.25), c(55.95, 55.86), resolution = 12)
a5_contains(edinburgh, points)

cap <- a5_spherical_cap(points, radius = 5000)
a5_overlaps(edinburgh, cap)

a5R documentation built on Oct. 19, 2026, 5:08 p.m.