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

Internally these use Arrow's zero-copy View() to reinterpret uint64 bytes as fixed_size_binary(8), then convert to/from the raw-byte representation used by a5_cell. 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"