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% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/colCollapse.R, R/rowCollapse.R
\name{colCollapse,DelayedMatrix-method}
\alias{colCollapse,DelayedMatrix-method}
\alias{rowCollapse,DelayedMatrix-method}
\title{Extract one cell from each row (column) of a matrix-like object}
\usage{
\S4method{colCollapse}{DelayedMatrix}(
x,
idxs,
cols = NULL,
force_block_processing = FALSE,
...,
useNames = TRUE
)
\S4method{rowCollapse}{DelayedMatrix}(
x,
idxs,
rows = NULL,
force_block_processing = FALSE,
...,
useNames = TRUE
)
}
\arguments{
\item{x}{A NxK \linkS4class{DelayedMatrix}.}
\item{idxs}{An index \code{\link{vector}} with the position to extract.
It is recycled to match the number of rows (column)}
\item{force_block_processing}{\code{FALSE} (the default) means that a
seed-aware, optimised method is used (if available). This can be overridden
to use the general block-processing strategy by setting this to \code{TRUE}
(typically not advised). The block-processing strategy loads one or more
(depending on \verb{\link[DelayedArray]\{getAutoBlockSize\}()}) columns (\code{colFoo()})
or rows (\code{rowFoo()}) into memory as an ordinary \link[base:array]{base::array}.}
\item{...}{Additional arguments passed to specific methods.}
\item{useNames}{If \code{\link{TRUE}} (default), names attributes of result are set. Else if \code{\link{FALSE}}, no naming support is done.}
\item{rows, cols}{A \code{\link{vector}} indicating the subset of rows
(and/or columns) to operate over. If \code{\link{NULL}}, no subsetting is
done.}
}
\value{
Returns a \code{\link{numeric}} \code{\link{vector}} of length N (K).
}
\description{
Extract one cell from each row (column) of a matrix-like object.
}
\details{
The S4 methods for \code{x} of type \code{\link{matrix}},
\code{\link{array}}, \code{\link{table}}, or \code{\link{numeric}} call
\code{matrixStats::\link[matrixStats]{rowCollapse}} /
\code{matrixStats::\link[matrixStats]{colCollapse}}.
}
\examples{
# A DelayedMatrix with a 'matrix' seed
dm_matrix <- DelayedArray(matrix(c(rep(1L, 5),
as.integer((0:4) ^ 2),
seq(-5L, -1L, 1L)),
ncol = 3))
# A DelayedMatrix with a 'HDF5ArraySeed' seed
# NOTE: Requires that the HDF5Array package is installed
library(HDF5Array)
dm_HDF5 <- writeHDF5Array(matrix(c(rep(1L, 5),
as.integer((0:4) ^ 2),
seq(-5L, -1L, 1L)),
ncol = 3))
# Extract the 4th row as a vector
# NOTE: An ordinary vector is returned regardless of the backend of
# the DelayedMatrix object
colCollapse(dm_matrix, 4)
colCollapse(dm_HDF5, 4)
# Extract the 2nd column as a vector
# NOTE: An ordinary vector is returned regardless of the backend of
# the DelayedMatrix object
rowCollapse(dm_matrix, 2)
rowCollapse(dm_HDF5, 2)
}
\seealso{
\itemize{
\item \code{matrixStats::\link[matrixStats:rowCollapse]{rowCollapse}()}
and \code{matrixStats::\link[matrixStats:rowCollapse]{colCollapse}()}
which are used when the input is a \code{matrix} or \code{numeric} vector.
}
}
\author{
Peter Hickey
}
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