H3 parent of a cell as plain SQL (no extension)

An H3 index stores its resolution in bits 52–55 and one 3-bit digit per resolution, unused digits set to 7. The parent at resolution res is therefore the same index with the resolution field rewritten and every finer digit set to 7 — pure bit arithmetic, which a browser without the h3 extension can run. Verified against h3_cell_to_parent() in the tests.

Usage

h3_parent_sql(hex, res)

Arguments

hex

SQL expression for a UBIGINT H3 cell.

res

target resolution (coarser than the cell's).

Value

A SQL expression string; NULL cells stay NULL.

Examples

h3_parent_sql("hex7", 5)
#> [1] "(((hex7 & ~(15::UBIGINT << 52)) | (5::UBIGINT << 52)) | ((1::UBIGINT << 30) - 1))"