specify spatial data as being gridded, or find out whether they are
returns logical (TRUE or FALSE) telling whether the object is gridded or not; in assignment promotes a non-gridded structure to a gridded one, or demotes a gridded structure back to a non-structured one.
gridded(obj) gridded(obj) <- TRUE fullgrid(obj) fullgrid(obj) <- TRUE gridparameters(obj)
- object deriviving from class "Spatial" (for gridded), or object of class SpatialGridDataFrame-class (for fullgrid and gridparameters)
- if obj derives from class Spatial, gridded(object) will tell
whether it is has topology on a regular grid; if assigned TRUE, if the
object derives from SpatialPoints and has gridded topology,
grid topology will be added to object, and the class of the object
will be promoted to SpatialGrid-class or
fullgridreturns a logical, telling whether the grid is full and ordered (i.e., in full matrix form), or whether it is not full or unordered (i.e. a list of points that happen to lie on a grid. If assigned, the way the points are stored may be changed. Changing a set of points to full matrix form and back may change the original order of the points, and will remove duplicate points if they were present.
objinherits from SpatialDataFrameGrid its grid parameters, else it returns numeric(0). The returned value is a data.frame with three columns, named cellcentre.offset ("lower left cell centre coordinates"), cellsize, and cells.dim (cell dimension); the rows correspond to the spatial dimensions.
# just 9 points on a grid: x <- c(1,1,1,2,2,2,3,3,3) y <- c(1,2,3,1,2,3,1,2,3) xy <- cbind(x,y) S <- SpatialPoints(xy) class(S) plot(S) gridded(S) <- TRUE gridded(S) class(S) summary(S) plot(S) gridded(S) <- FALSE gridded(S) class(S) # data.frame data(meuse.grid) coordinates(meuse.grid) <- ~x+y gridded(meuse.grid) <- TRUE plot(meuse.grid) # not much good summary(meuse.grid)