Matrix (version 1.5-1)

is.null.DN: Are the Dimnames dn NULL-like ?

Description

Are the dimnames dn NULL-like?

is.null.DN(dn) is less strict than is.null(dn), because it is also true (TRUE) when the dimnames dn are “like” NULL, or list(NULL,NULL), as they can easily be for the traditional R matrices (matrix) which have no formal class definition, and hence much freedom in how their dimnames look like.

Usage

is.null.DN(dn)

Value

logical

TRUE or FALSE.

Arguments

dn

dimnames() of a matrix-like R object.

Author

Martin Maechler

See Also

is.null, dimnames, matrix.

Examples

m <- matrix(round(100 * rnorm(6)), 2,3); m1 <- m2 <- m3 <- m4 <- m
dimnames(m1) <- list(NULL, NULL)
dimnames(m2) <- list(NULL, character())
dimnames(m3) <- rev(dimnames(m2))
dimnames(m4) <- rep(list(character()),2)

m4 ## prints absolutely identically to  m

stopifnot(m == m1, m1 == m2, m2 == m3, m3 == m4,
	  identical(capture.output(m) -> cm,
		    capture.output(m1)),
	  identical(cm, capture.output(m2)),
	  identical(cm, capture.output(m3)),
	  identical(cm, capture.output(m4)))

hasNoDimnames <- function(.) is.null.DN(dimnames(.))

stopifnot(exprs = {
  hasNoDimnames(m)
  hasNoDimnames(m1); hasNoDimnames(m2)
  hasNoDimnames(m3); hasNoDimnames(m4)
  hasNoDimnames(Matrix(m) -> M)
  hasNoDimnames(as(M, "sparseMatrix"))
})