Convert longitude/latitude to cell ID

Converts geographic coordinates to DGGS cell IDs using a grid specification.

Usage

lonlat_to_cell(lon, lat, grid)

Arguments

lon

Numeric vector of longitudes in degrees

lat

Numeric vector of latitudes in degrees

grid

A HexGridInfo or HexData object, or legacy hexify_grid

Value

Cell IDs: a bit64::integer64 vector for an ISEA grid, a character vector of H3 indices for an H3 grid

Details

ISEA cell IDs number a grid's cells from 1 and pass 2^53, the largest whole number a double holds exactly, at fine resolutions, so they are returned as 64-bit integers. Functions taking cell IDs also accept whole numbers below 2^53 and character strings of digits.

This function accepts either a HexGridInfo object from hex_grid() or a HexData object from hexify(). If a HexData object is provided, its grid specification is extracted automatically.

See also

cell_to_lonlat for the inverse operation, hex_grid for creating grid specifications

Examples

grid <- hex_grid(area_km2 = 1000)
cells <- lonlat_to_cell(lon = c(0, 10), lat = c(45, 50), grid = grid)

# Or use HexData object
df <- data.frame(lon = c(0, 10, 20), lat = c(45, 50, 55))
result <- hexify(df, lon = "lon", lat = "lat", area_km2 = 1000)
cells <- lonlat_to_cell(lon = 5, lat = 48, grid = result)