dimScale: Scale the Rows and Columns of a Matrix

In Matrix: Sparse and Dense Matrix Classes and Methods

Scale the Rows and Columns of a Matrix

Description

dimScale, rowScale, and colScale implement D1 %*% x %*% D2, D %*% x, and x %*% D for diagonal matrices D1, D2, and D with diagonal entries d1, d2, and d, respectively. Unlike the explicit products, these functions preserve dimnames(x) and symmetry where appropriate.

Usage

dimScale(x, d1 = sqrt(1/diag(x, names = FALSE)), d2 = d1)
rowScale(x, d)
colScale(x, d)

Arguments

x	a matrix, possibly inheriting from virtual class Matrix.
d1, d2, d	numeric vectors giving factors by which to scale the rows or columns of x; they are recycled as necessary.

Details

dimScale(x) (with d1 and d2 unset) is only roughly equivalent to cov2cor(x). cov2cor sets the diagonal entries of the result to 1 (exactly); dimScale does not.

Value

The result of scaling x, currently always inheriting from virtual class dMatrix.

It inherits from triangularMatrix if and only if x does. In the special case of dimScale(x, d1, d2) with identical d1 and d2, it inherits from symmetricMatrix if and only if x does.

Author(s)

Mikael Jagan

See Also

cov2cor

Examples

n <- 6L
(x <- forceSymmetric(matrix(1, n, n)))
dimnames(x) <- rep.int(list(letters[seq_len(n)]), 2L)

d <- seq_len(n)
(D <- Diagonal(x = d))

(scx <- dimScale(x, d)) # symmetry and 'dimnames' kept
(mmx <- D %*% x %*% D) # symmetry and 'dimnames' lost
stopifnot(identical(unname(as(scx, "generalMatrix")), mmx))

rowScale(x, d)
colScale(x, d)

Matrix documentation built on Oct. 19, 2024, 1:08 a.m.