The hardware and bandwidth for this mirror is donated by METANET, the Webhosting and Full Service-Cloud Provider.
If you wish to report a bug, or if you are interested in having us mirror your free-software or open-source project, please feel free to contact us at mirror[@]metanet.ch.

a5R

a5R provides R bindings for the A5 pentagonal geospatial index, powered by the a5 Rust crate via extendr.

A5 partitions the Earth’s surface into pentagonal cells across 31 resolution levels. Cells are equal-area, encoded as 64-bit integers, and achieve millimetre-level precision at the finest resolution.

Installation

install.packages("a5R")

Or install the development version from GitHub:

# install.packages("pak")
pak::pak("belian-earth/a5R")

You will need a working Rust toolchain (cargo and rustc).

Quick example

library(a5R)

# Index a point to a cell
cell <- a5_lonlat_to_cell(-3.19, 55.95, resolution = 10)
cell
#> <a5_cell[1]>
#> [1] 6344be8000000000

# Get the boundary polygon
a5_cell_to_boundary(cell)
#> <wk_wkb[1] with CRS=OGC:CRS84>
#> [1] <POLYGON ((-3.175718 55.93546, -3.145905 55.97569, -3.151641 56.01921, -3.219413 56.00818, -3.226037 55.96443, -3.175718 55.93546...>

# Navigate the hierarchy
a5_cell_to_parent(cell)
#> <a5_cell[1]>
#> [1] 6344be0000000000
a5_cell_to_children(cell)
#> <a5_cell[4]>
#> [1] 6344be2000000000 6344be6000000000 6344bea000000000 6344bee000000000

# Create a collection of cells whose centres fall within a great-circle distance of 100km from the origin cell
cells <- a5_spherical_cap(cell, radius = 100000) |> 
  a5_uncompact(resolution = 10)
plot(a5_cell_to_boundary(cells), col = "#206ead20", border = "#206ead", asp = 1)

A5 grid plot showing a collection of cells around a point

See vignette("a5R") for a full walkthrough of indexing, boundaries, hierarchy, traversal, and grid generation.

Features

Vectorised Rust core — all operations implemented in Rust and called from R via extendr. Benchmarks confirm identical results to the Python, JavaScript, and DuckDB A5 implementations.
vctrs + wk integration — cell indices use an a5_cell type with tibble support; geometries return as wk_wkb/wk_wkt vectors compatible with sf and terra.
Grid generation — a5_grid() fills any bounding box or geometry with cells at a target resolution using hierarchical flood-fill.
Traversal — a5_grid_disk() and a5_spherical_cap() select neighbours by hop count or great-circle distance.
Multi-threading — opt-in parallel processing via rayon for vectorised operations. See vignette("multithreading").

Acknowledgements

A5 was created by Felix Palmer. This package is a thin R wrapper around his work and would not exist without it. The Query-farm team maintain the DuckDB A5 extension, which wraps the same Rust crate and provided a valuable reference for this project.

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.