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

In Matrix: Sparse and Dense Matrix Classes and Methods

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)

Arguments

dn	dimnames() of a matrix-like R object.

Value

logical TRUE or FALSE.

Note

This function is really to be used on “traditional” matrices rather than those inheriting from Matrix, as the latter will always have dimnames list(NULL,NULL) exactly, in such a case.

Author(s)

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)))

Matrix documentation built on May 30, 2017, 1:20 a.m.

is.na(), is.infinite() Methods for 'Matrix' Objects

Matrix index

Methods for Function isSymmetric in Package 'Matrix'