dimnames {base} | R Documentation |
Retrieve or set the dimnames of an object.
dimnames(x) dimnames(x) <- value
x |
an R object, for example a matrix, array or data frame. |
value |
a possible value for dimnames(x) : see
“Value”. |
The functions dimnames
and dimnames<-
are generic.
For an array
(and hence in particular, for a
matrix
), they retrieve or set the dimnames
attribute (see attributes) of the object. A list
value
can have names, and these will be used to label the
dimensions of the array where appropriate.
The replacement method for arrays/matrices coerces vector and factor
elements of value
to character, but does not dispatch methods for
as.character
. It coerces zero-length elements to NULL
.
Both have methods for data frames. The dimnames of a data frame are
its row.names
and its names
. For the
replacement method each component of value
will be coerced by
as.character
.
For a 1D matrix the names
are the same thing as the
(only) component of the dimnames
.
The dimnames of a matrix or array can be NULL
or a list of the
same length as dim(x)
. If a list, its components are either
NULL
or a character vector with positive length of the
appropriate dimension of x
.
For the "data.frame"
method both dimnames are character
vectors, and the rownames must contain no duplicates nor missing values.
Setting components of the dimnames, e.g.
dimnames(A)[[1]] <- value
is a common paradigm, but note that
it will not work if the value assigned is NULL
. Use
rownames
instead, or (as it does) manipulate the whole
dimnames list.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
rownames
, colnames
;
array
, matrix
, data.frame
.
## simple versions of rownames and colnames ## could be defined as follows rownames0 <- function(x) dimnames(x)[[1]] colnames0 <- function(x) dimnames(x)[[2]]