retrieve (or set) spatial coordinates from (for) spatial data
list with (at least) two numeric components of equal length
data.frame with at least two numeric components
numeric matrix with at least two columns
object of, or deriving from, SpatialPoints
object of, or deriving from, SpatialPointsDataFrame
object of, or deriving from, SpatialPolygons
object of, or deriving from, SpatialPolygonsDataFrame
object of class Line; returned value is matrix
object of class Lines; returned value is list of matrices
object of, or deriving from, SpatialLines; returned value is list of lists of matrices
object of, or deriving from, GridTopology
object of, or deriving from, GridTopology
object of, or deriving from, SpatialPixels
object of, or deriving from, SpatialPixelsDataFrame
object of, or deriving from, SpatialGrid
object of, or deriving from, SpatialGridDataFrame
promote data.frame to object of class SpatialPointsDataFrame-class, by specifying coordinates; see coordinates