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\name{TsparseMatrix-class}
\title{Class "TsparseMatrix" of Sparse Matrices in Triplet Form}
%
\docType{class}
\keyword{array}
\keyword{classes}
%
\alias{TsparseMatrix-class}
%
\alias{coerce,matrix,TsparseMatrix-method}
\alias{coerce,vector,TsparseMatrix-method}
\alias{diag,TsparseMatrix-method}
\alias{diag<-,TsparseMatrix-method}
\alias{t,TsparseMatrix-method}
%
\description{The \code{"TsparseMatrix"} class is the virtual class of
all sparse matrices coded in triplet form. Since it is a virtual class,
no objects may be created from it. See
\code{showClass("TsparseMatrix")} for its subclasses.
}
\section{Slots}{
\describe{
\item{\code{Dim}, \code{Dimnames}:}{from the \code{"\linkS4class{Matrix}"} class,}
\item{\code{i}:}{Object of class \code{"integer"} - the row indices
of non-zero entries \emph{in 0-base}, i.e., must be in
\code{0:(nrow(.)-1)}.}
\item{\code{j}:}{Object of class \code{"integer"} - the column
indices of non-zero entries. Must be the same length as slot
\code{i} and \emph{0-based} as well, i.e., in
\code{0:(ncol(.)-1)}. For numeric Tsparse matrices, \code{(i,j)}
pairs can occur more than once, see \code{\linkS4class{dgTMatrix}}.
}
}
}
\section{Extends}{
Class \code{"sparseMatrix"}, directly.
Class \code{"Matrix"}, by class \code{"sparseMatrix"}.
}
\section{Methods}{
Extraction (\code{"["}) methods, see
\code{\link{[-methods}}.%-> ./Xtrct-methods.Rd
}
\note{
Most operations with sparse matrices are performed using the
compressed, column-oriented or \code{\linkS4class{CsparseMatrix}}
representation. The triplet representation is convenient for
creating a sparse matrix or for reading and writing such
matrices. Once it is created, however, the matrix is generally
coerced to a \code{\linkS4class{CsparseMatrix}} for further
operations.
Note that all \code{new(.)}, \code{\link{spMatrix}} and
\code{\link{sparseMatrix}(*, repr="T")} constructors
for \code{"TsparseMatrix"} classes implicitly add (i.e., \dQuote{sum up})
\eqn{x_k}'s that belong to identical \eqn{(i_k, j_k)} pairs, see, the
example below, or also \code{"\linkS4class{dgTMatrix}"}.
For convenience, methods for some operations such as \code{\%*\%}
and \code{crossprod} are defined for
\code{\linkS4class{TsparseMatrix}} objects. These methods simply
coerce the \code{\linkS4class{TsparseMatrix}} object to a
\code{\linkS4class{CsparseMatrix}} object then perform the
operation.
}
% \author{Martin Maechler}
\seealso{
its superclass, \code{\linkS4class{sparseMatrix}}, and the
\code{\linkS4class{dgTMatrix}} class, for the links to other classes.
}
\examples{
showClass("TsparseMatrix")
## or just the subclasses' names
names(getClass("TsparseMatrix")@subclasses)
T3 <- spMatrix(3,4, i=c(1,3:1), j=c(2,4:2), x=1:4)
T3 # only 3 non-zero entries, 5 = 1+4 !
\dontshow{stopifnot(nnzero(T3) == 3)}
}
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