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\name{DelayedAperm-class}
\alias{class:DelayedAperm}
\alias{DelayedAperm-class}
\alias{DelayedAperm}
\alias{is_noop,DelayedAperm-method}
\alias{summary.DelayedAperm}
\alias{summary,DelayedAperm-method}
\alias{dim,DelayedAperm-method}
\alias{dimnames,DelayedAperm-method}
\alias{extract_array,DelayedAperm-method}
\alias{is_sparse,DelayedAperm-method}
\alias{extract_sparse_array,DelayedAperm-method}
\alias{updateObject,SeedDimPicker-method}
\title{DelayedAperm objects}
\description{
NOTE: This man page is about \link{DelayedArray} internals and is provided
for developers and advanced users only.
The DelayedAperm class provides a formal representation of a
\emph{delayed "extended \code{aperm()}" operation}, that is, of a delayed
\code{\link[base]{aperm}()} that can drop and/or add \emph{ineffective}
dimensions. Note that since only \emph{ineffective} dimensions (i.e.
dimensions with an extent of 1) can be dropped or added, the length of
the output array is guaranteed to be the same as the length of the input
array.
DelayedAperm is a concrete subclass of the \link{DelayedUnaryOp} virtual
class, which itself is a subclass of the \link{DelayedOp} virtual class:
\preformatted{
DelayedOp
^
|
DelayedUnaryOp
^
|
DelayedAperm
}
DelayedAperm objects are used inside a \link{DelayedArray} object to
represent the \emph{delayed "extended \code{aperm()}" operations} carried
by the object. They're never exposed to the end user and are not intended
to be manipulated directly.
}
\usage{
\S4method{is_noop}{DelayedAperm}(x)
\S4method{summary}{DelayedAperm}(object, ...)
## ~ ~ ~ Seed contract ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
\S4method{dim}{DelayedAperm}(x)
\S4method{dimnames}{DelayedAperm}(x)
\S4method{extract_array}{DelayedAperm}(x, index)
## ~ ~ ~ Propagation of sparsity ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
\S4method{is_sparse}{DelayedAperm}(x)
\S4method{extract_sparse_array}{DelayedAperm}(x, index)
}
\arguments{
\item{x, object}{
A DelayedAperm object.
}
\item{index}{
See \code{?\link{extract_array}} for a description of the \code{index}
argument.
}
\item{...}{
Not used.
}
}
\seealso{
\itemize{
\item \link{DelayedOp} objects.
\item \code{\link{showtree}} to visualize the nodes and access the
leaves in the tree of delayed operations carried by a
\link{DelayedArray} object.
\item \code{\link{extract_array}} and \code{\link{extract_sparse_array}}.
}
}
\examples{
## DelayedAperm extends DelayedUnaryOp which extends DelayedOp:
extends("DelayedAperm")
## ---------------------------------------------------------------------
## BASIC EXAMPLES
## ---------------------------------------------------------------------
a0 <- array(1:20, dim=c(1, 10, 2))
A0 <- DelayedArray(a0)
showtree(A0)
A <- aperm(A0, perm=c(2, 3, 1))
showtree(A)
class(A@seed) # a DelayedAperm object
M1 <- drop(A0)
showtree(M1)
class(M1@seed) # a DelayedAperm object
M2 <- t(M1)
showtree(M2)
class(M2@seed) # a DelayedAperm object
## ---------------------------------------------------------------------
## PROPAGATION OF SPARSITY
## ---------------------------------------------------------------------
## DelayedAperm objects always propagate sparsity.
sa0 <- as(a0, "SparseArraySeed")
SA0 <- DelayedArray(sa0)
showtree(SA0)
is_sparse(SA0) # TRUE
SA <- aperm(SA0, perm=c(2, 3, 1))
showtree(SA)
class(SA@seed) # a DelayedAperm object
is_sparse(SA@seed) # TRUE
## ---------------------------------------------------------------------
## SANITY CHECKS
## ---------------------------------------------------------------------
stopifnot(class(A@seed) == "DelayedAperm")
stopifnot(class(M1@seed) == "DelayedAperm")
stopifnot(class(M2@seed) == "DelayedAperm")
stopifnot(class(SA@seed) == "DelayedAperm")
stopifnot(is_sparse(SA@seed))
}
\keyword{methods}
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