| row+colnames {base} | R Documentation |
Row and Column Names
Description
Retrieve or set the row or column names of a matrix-like object.
Usage
rownames(x, do.NULL = TRUE, prefix = "row")
rownames(x) <- value
colnames(x, do.NULL = TRUE, prefix = "col")
colnames(x) <- value
Arguments
x |
a matrix-like R object, with at least two dimensions for
|
do.NULL |
logical. If |
prefix |
for created names. |
value |
a valid value for that component of
|
Details
The extractor functions try to do something sensible for any
matrix-like object x. If the object has dimnames
the first component is used as the row names, and the second component
(if any) is used for the column names. For a data frame, rownames
and colnames eventually call row.names and
names respectively, but the latter are preferred.
If do.NULL is FALSE, a character vector (of length
NROW(x) or NCOL(x)) is returned in any
case, prepending prefix to simple numbers, if there are no
dimnames or the corresponding component of the dimnames is NULL.
The replacement methods for arrays/matrices coerce vector and factor
values of value to character, but do not dispatch methods for
as.character.
For a data frame, value for rownames should be a
character vector of non-duplicated and non-missing names (this is
enforced), and for colnames a character vector of (preferably)
unique syntactically-valid names. In both cases, value will be
coerced by as.character, and setting colnames
will convert the row names to character.
Note
If the replacement versions are called on a matrix without any existing dimnames, they will add suitable dimnames. But constructions such as
rownames(x)[3] <- "c"
may not work unless x already has dimnames, since this will
create a length-3 value from the NULL value of
rownames(x).
See Also
dimnames,
case.names,
variable.names.
Examples
m0 <- matrix(NA, 4, 0)
rownames(m0)
m2 <- cbind(1, 1:4)
colnames(m2, do.NULL = FALSE)
colnames(m2) <- c("x","Y")
rownames(m2) <- rownames(m2, do.NULL = FALSE, prefix = "Obs.")
m2