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\name{marginSumsSparse}
\alias{marginSumsSparse}
\title{
Margin Sums of a Sparse Matrix or Sparse Array
}
\description{
For a sparse matrix or sparse array, compute the sum of array entries
for a specified margin or margins.
}
\usage{
marginSumsSparse(X, MARGIN)
}
\arguments{
\item{X}{
A matrix, an array,
a sparse matrix (of class \code{"sparseMatrix"} from the
\pkg{Matrix} package) or a sparse three-dimensional array
(of class \code{"sparse3Darray"} from the
\pkg{spatstat.sparse} package).
}
\item{MARGIN}{
Integer or integer vector specifying the margin or margins.
}
}
\details{
This function computes the equivalent of
\code{\link[base]{apply}(X, MARGIN, sum)}
for sparse matrices and arrays \code{X}. The argument \code{X} may be
\itemize{
\item a matrix
\item an array of any number of dimensions
\item a sparse matrix (object inheriting class \code{"sparseMatrix"}
in the \pkg{Matrix} package)
\item a sparse three-dimensional array (of class
\code{"sparse3Darray"}
from the \pkg{spatstat.sparse} package).
}
In the first two cases, the computation is performed by
calling \code{\link[base]{apply}(X, MARGIN, sum)}
and the result is a vector, matrix or array.
In the last two cases, the result is a single value, a sparse vector,
a sparse matrix, or a sparse three-dimensional array.
}
\value{
A single value, vector, matrix, array,
sparse vector (class \code{"sparseVector"} in the \pkg{Matrix}
package), sparse matrix (class \code{"sparseMatrix"} in the
\pkg{Matrix} package), or sparse three-dimensional array
(class \code{"sparse3Darray"}
from the \pkg{spatstat.sparse} package).
}
\author{
\spatstatAuthors.
}
\seealso{
\code{\link[base]{apply}}
}
\examples{
M <- sparse3Darray(i=1:3, j=c(3,1,2), k=4:2,
x=round(runif(3), 2), dims=rep(4, 3))
marginSumsSparse(M, 1:2)
marginSumsSparse(M, 1)
marginSumsSparse(M, integer(0)) # equivalent to sum(M)
}
\keyword{array}
\keyword{algebra}
\keyword{manip}
\concept{sparse}
|
