Matrix (version 1.4-0)

unpack: Representation of Packed and Unpacked (Dense) Matrices

Description

“Packed” matrix storage here applies to dense matrices ('>denseMatrix) only, and there is available only for symmetric ('>symmetricMatrix) or triangular ('>triangularMatrix) matrices, where only one triangle of the matrix needs to be stored.

unpack() unpacks “packed” matrices, where pack() produces “packed” matrices.

Usage

pack(x, …)
# S4 method for matrix
pack(x, symmetric = NA, upperTri = NA, …)
unpack(x, …)

Arguments

x

for unpack():

a matrix stored in packed form, e.g., of class "d?pMatrix" where "?" is "t" for triangular or "s" for symmetric.

for pack():

a (symmetric or triangular) matrix stored in full storage.

symmetric

logical (including NA) for optionally specifying if x is symmetric (or rather triangular).

upperTri

(for the triangular case only) logical (incl. NA) indicating if x is upper (or lower) triangular.

…

further arguments passed to or from other methods.

Value

for unpack():

A '>Matrix object containing the full-storage representation of x.

for pack():

A packed Matrix (i.e. of class "..pMatrix") representation of x.

Details

These are generic functions with special methods for different types of packed (or non-packed) symmetric or triangular dense matrices. Use showMethods("unpack") to list the methods for unpack(), and similarly for pack().

Examples

# NOT RUN {
showMethods("unpack")
(cp4 <- chol(Hilbert(4))) # is triangular
tp4 <- as(cp4,"dtpMatrix")# [t]riangular [p]acked
str(tp4)
(unpack(tp4))
stopifnot(identical(tp4, pack(unpack(tp4))))

(s <- crossprod(matrix(sample(15), 5,3))) # traditional symmetric matrix
(sp <- pack(s))
mt <- as.matrix(tt <- tril(s))
(pt <- pack(mt))
stopifnot(identical(pt, pack(tt)),
	  dim(s ) == dim(sp), all(s  == sp),
	  dim(mt) == dim(pt), all(mt == pt), all(mt == tt))
showMethods("pack")
# }