gridded-methods {sp} | R Documentation

## specify spatial data as being gridded, or find out whether they are

### Description

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.

### Usage

            gridded(obj)
            gridded(obj) <- TRUE
            fullgrid(obj)
            fullgrid(obj) <- TRUE
            gridparameters(obj)

### Arguments

`obj` | object deriviving from class "Spatial" (for gridded), or

object of class SpatialGridDataFrame-class (for fullgrid and gridparameters)

### Value

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 SpatialGridDataFrame-class
`fullgrid` returns 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.
`gridparameters` returns, if `obj` inherits 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.

### Methods

obj = "Spatial"
  object deriviving from class "Spatial"

### Examples

    # 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)

[Package sp version 0.7-12 Index]