Define a uniform grid for a partitioned spatial join

Describes the regular grid that spatial_join() uses to partition two streamed layers for the both-sides-larger-than-RAM case. Cell (cx, cy) covers [origin_x + cx * cellsize_x, origin_x + (cx + 1) * cellsize_x) and likewise in y, so a coordinate maps to the cell floor((coord - origin) / cellsize). Pick a cellsize comparable to the scale of the join (large enough that most cells hold a workable shard, small enough that one cell's features fit in memory); for an extended-on-extended join choose it larger than the left features.

Usage

grid(cellsize, origin = c(0, 0))

Arguments

cellsize

Cell size: a single number for square cells, or c(cellsize_x, cellsize_y).

origin

Grid origin c(x0, y0) (a cell corner). Default c(0, 0).

Value

A vectra_grid specification to pass as spatial_join(partition =).

See also

spatial_join() for the join it partitions.

Examples

grid(1000)
grid(c(0.5, 0.25), origin = c(-180, -90))