Column Indexes

Usage

col(x, as.factor=FALSE)

Arguments

x a matrix.
as.factor a logical value indicating whether the value should be returned as a factor rather than as numeric.

Value

An integer matrix with the same dimensions as x and whose ij-th element is equal to j.

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,nr=5,nc=5)
x[row(x)==col(x)] <- 1

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