row {base}

R Documentation

Row Indexes

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

x	a matrix-like object, that is one with a two-dimensional dim.
dim	a matrix dimension, i.e., an integer valued numeric vector of length two (with non-negative entries).
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 x and whose ij-th element is equal to i (or the i-th row label).

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

col to get columns; 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"

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