NEWS

---

a5R 0.4.0.9000

a5R 0.4.0 (2026-05-14)

• a5_grid() is soft-deprecated in favour of a5_polygon_to_cells(). Calling it now emits a lifecycle::deprecate_warn() with guidance: use a5_polygon_to_cells() for geometry inputs (centre-in-polygon containment), or pass a wk::rct() bounding box for the bbox use case. Note that the two functions are not semantically identical: a5_grid() uses boundary intersection (any cell touched by the geometry), whereas a5_polygon_to_cells() uses centre-point containment (cells whose centroid lies inside).
• New a5_polygon_to_cells() returns the A5 cells whose centres lie inside a polygon. Distinct from a5_grid(), which uses boundary-intersection semantics. Accepts wk-handleable geometries (including MULTIPOLYGON and sfc of several polygons), terra SpatVector objects, numeric matrices, or data.frame(lon, lat). Multi-part inputs are handled natively: per polygon part the outer ring's cells are computed and any hole-ring cells are subtracted, then the results are unioned across parts and recompacted.
• New a5_linestring_to_cells() returns the A5 cells whose pentagons are intersected by a great-circle polyline, in discovery order along the path. Accepts the same input shapes as a5_polygon_to_cells(), including MULTILINESTRING, sfcs of multiple linestrings, and terra SpatVector objects; per-feature outputs are concatenated with first-seen deduplication.
• Bumped the embedded a5 Rust crate from 0.7.0 to 0.8.0. Transparent improvements inherited from upstream: resolution-30 (de)serialisation (a5 0.7.1), neighbour functions at resolutions 0 and 1 (a5 0.7.2), longitude normalisation in cell_to_lonlat (a5 0.7.3), faster cell_to_parent, and a polar-region spiral fix in grid_disk and spherical_cap.
• Breaking: a5_cell_to_lonlat() replaces its normalise argument with as_dataframe (default FALSE). When FALSE, centroids are returned as a wk::xy() vector with WGS 84 CRS; when TRUE, as a base data.frame with lon/lat columns. The previous normalise argument toggled longitude normalisation, but upstream a5 (>= 0.7.3) always returns normalised longitudes, so the flag's effective job collapsed to "what container?". as_dataframe makes that explicit. Defaults are unchanged for users who never set normalise (still returns wk::xy); explicit normalise = TRUE/FALSE calls now error and must be updated.
• New lifecycle dependency added to Imports.

a5R 0.3.1 (2026-03-26)

• a5_cell() now requires hex strings to be exactly 16 characters, preventing silent construction of wrong cells from truncated input.
• Improved vignettes covering the new a5_cell representation and Arrow integration.

a5R 0.3.0

• a5_cell internal representation now uses 8 parallel raw byte vectors instead of hex strings, reducing memory from ~80 bytes/cell to 8 bytes/cell (#12).
• a5_cell gains vec_proxy_compare() and vec_proxy_order() methods, enabling sort(), order(), unique(), duplicated(), match(), and %in% (#12).
• a5_cell gains an is.na() method (#12).
• New a5_cell_from_arrow() and a5_cell_to_arrow() for lossless conversion between a5_cell and Arrow uint64 arrays, enabling zero-copy Parquet I/O (#12).
• New a5_u64_to_hex() and a5_hex_to_u64() for explicit conversion between a5_cell vectors and hex strings.
• a5_is_cell() has been renamed to a5_is_valid() and now accepts both a5_cell vectors and character hex strings.
• a5_cell_distance() and a5_cell_area() gain a units = NULL option to return plain numeric vectors without units class overhead.
• New vignettes: vignette("internal-cell-representation") and vignette("arrow-parquet").

a5R 0.2.0 (2026-03-16)

• Initial CRAN submission.