a5_resolution_stats: Cell size and counts by resolution

In a5R: 'A5' Discrete Global Grid System

Cell size and counts by resolution

Description

Properties of the grid at a resolution, independent of any particular cell:

Usage

a5_cell_area(resolution, units = "m^2")

a5_cell_edge_length_avg(resolution, units = "m")

a5_get_num_cells(resolution)

a5_get_num_children(parent_resolution, child_resolution)

Arguments

resolution	Integer vector of resolutions (0–30). A scalar for a5_get_num_cells().
units	Character scalar giving the output unit: an area unit for a5_cell_area() (default "m^2"), a length unit for a5_cell_edge_length_avg() (default "m"). Any unit units::set_units() can convert to is accepted (e.g. "km^2", "ha", "km", "mi"). If NULL, a plain numeric vector in square metres or metres is returned.
parent_resolution, child_resolution	Integer scalars (0–30), with child_resolution at or finer than parent_resolution.

Details

• a5_cell_area(): the area of one cell. A5 is an equal-area grid, so every cell at a resolution has the same area.

• a5_cell_edge_length_avg(): the average cell edge length. Individual edges vary from this by roughly +/-10%, depending on the cell's shape and position; use a5_cell_to_boundary() to measure a specific cell.

• a5_get_num_cells(): the number of cells covering the globe.

• a5_get_num_children(): the number of descendants each cell has at a finer resolution, as returned by a5_cell_to_children().

Use the first two to choose a resolution for a target cell size.

Value

• a5_cell_area(), a5_cell_edge_length_avg(): a units::units vector the length of resolution, or numeric when units = NULL.

• a5_get_num_cells(), a5_get_num_children(): a numeric scalar. Counts are doubles because they can exceed R's integer range.

Examples

a5_cell_area(0:5)
a5_cell_area(5, units = "km^2")
a5_cell_edge_length_avg(10, units = "km")

a5_get_num_cells(10)
a5_get_num_children(5, 8) # 4^3 = 64

# cells at a resolution times their area covers the globe
a5_get_num_cells(10) * a5_cell_area(10, units = "km^2")

a5R documentation built on Oct. 19, 2026, 5:08 p.m.