| col {base} | R Documentation |
Column Indexes
Description
Returns a matrix of integers indicating their column number in a matrix-like object, or a factor of column labels.
Usage
col(x, as.factor = FALSE)
.col(dim)
Arguments
x |
a matrix-like object, that is one with a two-dimensional
|
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 column 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 j (or the j-th column label).
References
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
See Also
row to get rows;
slice.index for a general way to get slice indices
in an array.
Examples
# extract an off-diagonal of a matrix
ma <- matrix(1:12, 3, 4)
ma[row(ma) == col(ma) + 1]
# 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
(i34 <- .col(3:4))
stopifnot(identical(i34, .col(c(3,4)))) # 'dim' maybe "double"
[Package base version 4.4.1 Index]