| % File src/library/base/man/row.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2018 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{row} |
| \title{Row Indexes} |
| \alias{row} |
| \alias{.row} |
| \description{ |
| Returns a matrix of integers indicating their row number in a |
| matrix-like object, or a factor indicating the row labels. |
| } |
| \usage{ |
| row(x, as.factor = FALSE) |
| .row(dim) |
| } |
| \arguments{ |
| \item{x}{a matrix-like object, that is one with a two-dimensional |
| \code{dim}.} |
| \item{dim}{a matrix dimension, i.e., an integer valued numeric vector of |
| length two (with non-negative entries).} |
| \item{as.factor}{a logical value indicating whether the value should |
| be returned as a factor of row labels (created if necessary) |
| rather than as numbers.} |
| } |
| \value{ |
| An integer (or factor) matrix with the same dimensions as \code{x} and whose |
| \code{ij}-th element is equal to \code{i} (or the \code{i}-th row label). |
| } |
| \references{ |
| Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) |
| \emph{The New S Language}. |
| Wadsworth & Brooks/Cole. |
| } |
| \seealso{ |
| \code{\link{col}} to get columns; |
| \code{\link{slice.index}} for a general way to get slice indices |
| in an array. |
| } |
| \examples{ |
| x <- matrix(1:12, 3, 4) |
| # extract the diagonal of a matrix - more slowly than diag(x) |
| dx <- x[row(x) == col(x)] |
| dx |
| |
| # create an identity 5-by-5 matrix more slowly than diag(n = 5): |
| x <- matrix(0, nrow = 5, ncol = 5) |
| x[row(x) == col(x)] <- 1 |
| x |
| |
| (i34 <- .row(3:4)) |
| stopifnot(identical(i34, .row(c(3,4)))) # 'dim' maybe "double" |
| } |
| \keyword{array} |