Dimnames Attribute of an Object

DESCRIPTION:

Returns or changes the dimnames attribute of an array. This is a list of the same length as the dimension of the array.

USAGE:

dimnames(x) 
dimnames(x) <- value 

REQUIRED ARGUMENTS:

x
any object.

OPTIONAL ARGUMENTS:

value
list of the same length as dim(x), or NULL, whose components have length equal to the corresponding dimension or zero.

VALUE:

the dimension names of x if they exist, or NULL.

The dimnames of an object is a list whose length is length(dim(x)). The ith element of dimnames(x) is either of length 0 (not allowed for data frames or bdFrames) or is a vector of dim(x)[i] character strings, and in the latter case should be thought of as a set of labels for the ith dimension of x.

SIDE EFFECTS:

in the assignment form, the dimnames attribute of x is created or changed if x is an array or data frame and value is compatible with dim(x).

DETAILS:

This is a generic function, there is a method for data frames and bdFrames. Arrays (may) have a dimnames attribute, and this is what is reported on or changed. The dimnames of a data frame or bdFrame are the row.names attribute and the names of the object.

To explicitly delete the dimnames attribute of an array (or matrix), use dimnames(x)<-NULL. To explicitly delete row or column names, see example below.

You may not remove the dimnames of a data frame or bdFrame. The row and column names must have the same length as the number or rows and columns of the data frame or bdFrame. Column names must be unique; row names must be unique unless the data frame or bdFrame has a non- NULL dup.row.names attribute.

The value may be a character vector, or anything that can be coerced to a character vector. However, it should not be a bdCharacter or other bdVector; you can convert these to an ordinary vector using bd.coerce

Instead of using names to replace row names from a matrix, use rowIds or dimnames.

NOTE:

Array subscripts retain dimnames; see Subscript.

SEE ALSO:

, , , , , , , .

EXAMPLES:

dimnames(iris)[[3]]        # iris species 
my.matrix <- matrix(1:12, 3)
dimnames(my.matrix) <- list(NULL, c("red", "blue", "brown", "green")) 
dimnames(my.matrix)[[1]] <- c("a", "b", "c")  # add row names
dimnames(my.matrix)[[1]] <- character(0)      # remove row names
dimnames(my.matrix)[[2]] <- c("d", "e", "f", "g")  # change col names
# Note -- when creating dimnames initially you may use NULL as
# as a shortcut for character(0), but not when modifying dimnames.
# This is illegal:  dimnames(my.matrix)[[1]] <- NULL