Convert between a5_cell and Arrow uint64 arrays

Losslessly convert between a5_cell vectors and Arrow uint64 arrays. This avoids the precision loss that occurs when Arrow converts uint64 to R's double (which can only represent integers exactly up to 2^53, while A5 cell IDs span the full 0–2^64 range).

Usage

a5_cell_from_arrow(x)

a5_cell_to_arrow(x)

Arguments

x

For a5_cell_from_arrow(), an Arrow Array or ChunkedArray of type uint64. For a5_cell_to_arrow(), an a5_cell vector.

Value

a5_cell_from_arrow() returns an a5_cell vector. a5_cell_to_arrow() returns an Arrow Array of type uint64.

Details

The conversion runs in Rust and passes one contiguous uint64 buffer through the Arrow C data interface, so no value is ever converted to double. NA cells are null elements. The resulting Arrow arrays can be written directly to Parquet and read correctly by DuckDB, Python, and other Arrow-compatible tools.

See also

a5_u64_to_hex() for converting to hex strings instead.

Examples

cell <- a5_lonlat_to_cell(135, 0, resolution = 10)
arr <- a5_cell_to_arrow(cell)
back <- a5_cell_from_arrow(arr)
identical(format(cell), format(back))
#> [1] TRUE
cells <- a5_lonlat_to_cell(c(-3.19, 135), c(55.95, 0), resolution = 10)
arr <- a5_cell_to_arrow(cells)
arr$type$ToString()
#> [1] "uint64"