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col {base}

Column Indexes
Package: 
base
Version: 
R 3.0.1

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)

Arguments

x
a matrix-like object, that is one with a two-dimensional dim.
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.

Values

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.

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
x <- matrix(0, nrow = 5, ncol = 5)
x[row(x) == col(x)] <- 1

Documentation reproduced from R 3.0.1. License: GPL-2.