row+colnames | R Documentation |
Retrieve or set the row or column names of a matrix-like object.
rownames(x, do.NULL = TRUE, prefix = "row") rownames(x) <- value colnames(x, do.NULL = TRUE, prefix = "col") colnames(x) <- value
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
|
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.
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)
.
dimnames
,
case.names
,
variable.names
.
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
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