is.null.DN {Matrix} | R Documentation |

## 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)

### Arguments

### 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)))

[Package

*Matrix* version 1.2-17

Index]