Description Usage Arguments Details Value References See Also Examples
Functions to get or set the names of an object.
1 2 | ## S4 method for signature 'FileClass'
names(x)
|
x |
an R object. |
names
is a generic accessor function, and names<-
is a
generic replacement function. The default methods get and set
the "names"
attribute of a vector (including a list) or
pairlist.
For an environment
env
, names(env)
gives
the names of the corresponding list, i.e.,
names(as.list(env, all.names = TRUE))
which are also given by
ls(env, all.names = TRUE, sorted = FALSE)
. If the
environment is used as a hash table, names(env)
are its
“keys”.
If value
is shorter than x
, it is extended by character
NA
s to the length of x
.
It is possible to update just part of the names attribute via the
general rules: see the examples. This works because the expression
there is evaluated as z <- "names<-"(z, "[<-"(names(z), 3, "c2"))
.
The name ""
is special: it is used to indicate that there is no
name associated with an element of a (atomic or generic) vector.
Subscripting by ""
will match nothing (not even elements which
have no name).
A name can be character NA
, but such a name will never be
matched and is likely to lead to confusion.
Both are primitive functions.
For names
, NULL
or a character vector of the same length
as x
. (NULL
is given if the object has no names,
including for objects of types which cannot have names.) For an
environment, the length is the number of objects in the environment
but the order of the names is arbitrary.
For names<-
, the updated object. (Note that the value of
names(x) <- value
is that of the assignment, value
, not
the return value from the left-hand side.)
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | # print the names attribute of the islands data set
names(islands)
# remove the names attribute
names(islands) <- NULL
islands
rm(islands) # remove the copy made
z <- list(a = 1, b = "c", c = 1:3)
names(z)
# change just the name of the third element.
names(z)[3] <- "c2"
z
z <- 1:3
names(z)
## assign just one name
names(z)[2] <- "b"
z
|
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