\HeaderA{gridded-methods}{specify spatial data as being gridded, or find out whether they are}{gridded.Rdash.methods}
\aliasA{fullgrid}{gridded-methods}{fullgrid}
\aliasA{fullgrid<\Rdash}{gridded-methods}{fullgrid<.Rdash.}
\aliasA{gridded}{gridded-methods}{gridded}
\aliasA{gridded,Spatial-method}{gridded-methods}{gridded,Spatial.Rdash.method}
\aliasA{gridded<\Rdash}{gridded-methods}{gridded<.Rdash.}
\aliasA{gridparameters}{gridded-methods}{gridparameters}
\keyword{methods}{gridded-methods}
\keyword{spatial}{gridded-methods}
\begin{Description}\relax
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.
\end{Description}
\begin{Usage}
\begin{verbatim}
        gridded(obj)
        gridded(obj) <- TRUE
        fullgrid(obj)
        fullgrid(obj) <- TRUE
        gridparameters(obj)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{obj}] object deriviving from class "Spatial" (for gridded), or 
\end{ldescription}

object of class \LinkA{SpatialGridDataFrame-class}{SpatialGridDataFrame.Rdash.class} (for fullgrid and gridparameters)
\end{Arguments}
\begin{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 \LinkA{SpatialGrid-class}{SpatialGrid.Rdash.class} or 
\LinkA{SpatialGridDataFrame-class}{SpatialGridDataFrame.Rdash.class}

\code{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.

\code{gridparameters} returns, if \code{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.
\end{Value}
\begin{Section}{Methods}
\describe{
\item[obj = "Spatial"] object deriviving from class "Spatial" 
}
\end{Section}
\begin{Examples}
\begin{ExampleCode}
# 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)

\end{ExampleCode}
\end{Examples}

