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Cell id at a longitude/latitude (inverse of cell_lonlat())

Source: R/grid.R
cell_from_lonlat.Rd

Pure arithmetic on the grid definition – no raster read. The cell-id COGs are lookup IMAGES whose band name and frame vary by grid, so resolving a click by reading one is both slower and a source of bugs: selecting the band by name fails (usa05 calls it r_cellid, global05 depth_mean), and shifting a click to 0-360 lands outside a raster stored in -180..180. The grid registry already defines the mapping exactly.

Usage

cell_from_lonlat(lon, lat, grid)

Arguments

lon, lat

coordinates in degrees, lon in -180..180

grid

grid spec from grid_spec_for()

Value

cell id, or NA where the point falls outside the grid