Convert between a5_covering and Arrow list<uint64> arrays

Losslessly convert a5_covering vectors to and from Arrow list<uint64> arrays, one list element per covering. Each element holds the covering's compacted cells followed by its compaction marker, the layout every A5 library uses, so the resolution travels with the data into Parquet, DuckDB, Python or JavaScript. A missing covering is a null element.

Usage

a5_covering_from_arrow(x)

a5_covering_to_arrow(x)

Arguments

x

For a5_covering_from_arrow(), an Arrow Array or ChunkedArray of type list<uint64>. For a5_covering_to_arrow(), an a5_covering vector.

Value

a5_covering_from_arrow() returns an a5_covering vector. a5_covering_to_arrow() returns an Arrow Array of type list<uint64>.

Details

a5_covering_from_arrow() accepts coverings written by any A5 library. Each one is checked, sorted and compacted; an element without a compaction marker stands for the resolution of its finest cell.

See also

a5_cell_to_arrow() for single cells.

Examples

cells <- a5_lonlat_to_cell(c(-3.19, 135), c(55.95, 0), resolution = 10)
disks <- a5_grid_disk(cells, k = 2)
arr <- a5_covering_to_arrow(disks)
arr$type$ToString()
#> [1] "list<item: uint64>"
identical(a5_covering_from_arrow(arr), disks)
#> [1] TRUE