HexGridInfo Class

An S4 class representing a hexagonal grid specification. Stores all parameters needed for grid operations.

Details

Create HexGridInfo objects using the hex_grid constructor function. Do not use new("HexGridInfo", ...) directly.

The aperture can be "3", "4", "7" for grids that refine by one aperture at every level; a family name such as "4/3" or "4/7", which refines by the first aperture for the first floor(resolution / 2) levels and by the second for the rest; or one aperture per level, "4,4,7,3". The separator tells the two apart: "4,7" and the family "4/7" are the same grid at resolution 2, but their grids one level coarser are "4" and "7".

For H3 grids, the aperture is fixed at "7" and resolution ranges from 0 to 15.

Slots

aperture: Character. Grid aperture: "3", "4", "7", a mixed family such as "4/3" or "4/7", or one aperture per resolution level ("4,4,7,3").
resolution: Integer. Grid resolution level: for ISEA 0-30 for aperture 3, 0-29 for aperture 4, 0-21 for aperture 7 on the icosahedron (cell IDs fit in 64 bits); 0-15 for H3.
area_km2: Numeric. Cell area in square kilometers.
diagonal_km: Numeric. Centre spacing in kilometers: the short (flat-to-flat) diagonal of a regular hexagon of area area_km2, \(\sqrt{2A/\sqrt{3}}\).
crs: Integer or character. Coordinate reference system: an EPSG code, or a 'PROJ' or 'WKT' string. Defaults to 'WGS84' on Earth, and to a longlat CRS on the sphere of radius_km on any other body.
grid_type: Character. Grid system: "isea" (default) or "h3".
radius_km: Numeric. Radius of the body the grid covers, in kilometers. NA reads as Earth's mean radius.
orientation: Numeric. Where an ISEA grid's solid sits: c(vert0_lon, vert0_lat, azimuth) in degrees, vertex 0 and the azimuth of vertex 1 seen from it. Empty for H3 grids, whose orientation H3 fixes.
projection: Character. How an ISEA-family grid projects each face of its solid onto its plane triangle: "isea" (Snyder's equal-area projection) or "fuller" (Fuller's projection). Empty for H3 grids.
polyhedron: Character. The solid an ISEA-family grid is built on: "icosahedron" or "octahedron". Empty for H3 grids.

Details

Slots

See also