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\name{modelMatrix-class}
\Rdversion{1.1}
\title{Class "modelMatrix" and SubClasses}
\docType{class}
\alias{modelMatrix-class}
\alias{denseModelMatrix-class}
\alias{ddenseModelMatrix-class}
\alias{sparseModelMatrix-class}
\alias{dsparseModelMatrix-class}
%
\alias{show,modelMatrix-method}
\alias{print,modelMatrix-method}
\description{
The class \code{"modelMatrix"} and notably its subclass
\code{"dsparseModelMatrix"} are used to encode additional information,
analogously to what the standard \R function
\code{\link{model.matrix}()} returns.
}
\section{Objects from the Classes}{
Only \code{"dsparseModelMatrix"} and \code{"ddenseModelMatrix"} are
\dQuote{actual} (aka non-virtual) classes. For these,
objects can be created by calls of the form
\code{new("dsparseModelMatrix", x, assign, contrast)}, where \code{x}
is a \code{\link[Matrix:dgCMatrix-class]{dgCMatrix}} classed object.
}
\section{Slots}{
The \code{"modelMatrix"} mother class contains
\code{\link[Matrix:Matrix-class]{Matrix}} (pkg \CRANpkg{Matrix}) plus two extra slots,
\describe{
\item{\code{assign}:}{\code{"integer"} vector of length
\code{ncol(.)}, coding the variables which make up the
matrix columns, see \code{\link{model.matrix}}.}
\item{\code{contrasts}:}{a named \code{\link{list}} of
\code{\link{contrasts}}, as in \code{\link{model.matrix}()}.}
\item{\code{Dim}:}{integer vector of length two with the matrix dimensions.}
\item{\code{Dimnames}:}{list of length two, the
\code{\link{dimnames}(.)} of the matrix.}
}
whereas the (current only) actual classes \code{"d*ModelMatrix"},
have an at least an additional (\code{\link{numeric}} slot \code{"x"}.
E.g., "dsparseModelMatrix" has the additional slots
\describe{
\item{\code{i},\code{p}:}{row number and \dQuote{pointer} integer
vectors, see class \code{"\link[Matrix:dgCMatrix-class]{dgCMatrix}"}.}
\item{\code{x}:}{\code{"numeric"} vector of non-zero entries.}
\item{\code{factors}:}{a (possibly empty) \code{\link{list}} of
factorizations.}
}
}
\section{Extends}{
\code{"dsparseModelMatrix"} extends class \code{"\link[Matrix:dgCMatrix-class]{dgCMatrix}"} directly,\cr
\code{"ddenseModelMatrix"} extends class \code{"\link[Matrix:dgeMatrix-class]{dgeMatrix}"} directly.
}
\section{Methods}{
\describe{
\item{show}{\code{signature(object = "modelMatrix")}:
\code{\link{show}(.)} the matrix, but also the \code{assign} and
\code{contrasts} slots.}
\item{print}{\code{signature(x = "modelMatrix")}: as \code{show()},
however (via \code{\dots}) allowing to pass further arguments for
printing the matrix.% notably those of (currently hidden !!)
% \code{\link{printSpMatrix}()}.
}
}
}
\author{Martin Maechler}
\seealso{
\code{\link[Matrix]{sparse.model.matrix}} (pkg \CRANpkg{Matrix}) will return a
\code{"\link[Matrix:dgCMatrix-class]{dgCMatrix}"} object.
\code{\link{model.Matrix}} is a simple wrapper around the traditional
\code{\link{model.matrix}} and returns a \code{"ddenseModelMatrix"} object.
}
\examples{
showClass("modelMatrix")
showClass("dsparseModelMatrix")
## see example(model.Matrix)
}
\keyword{classes}
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