character
Character Objects
Description
Creates or tests for objects of mode character.
Usage
character(length = 0L)
is.character(x)
as.character(x, ...)
Arguments
| length |
integer giving the length of the returned object.
|
| ... |
additional arguments passed to the generic method.
|
| x |
any S object.
|
Details
is.character is not generic.
as.character is generic and has a method implemented for class factor.
The default method of as.character calls as.vector(x, mode="character").
Note that as.vector is generic.
Simple objects have no attributes.
Data elements of objects of mode "character" are character strings.
In most R expressions, it is not necessary to ensure explicitly that data
are of a particular mode. For example, the function paste does
not need character arguments; it coerces data to character as needed.
Note the difference between coercing to a simple object of mode "character"
and setting the mode attribute:
mode(myobject) <- "character"
This example changes the mode of myobject but leaves all other attributes unchanged.
(For example, a matrix stays a matrix.)
Note that the value of as.character(myobject) has no attributes.
If you use ascii codes in a character string, "\n" denotes an ascii
newline character and "\t" denotes an ascii tab character.
"\\" denotes a backslash, and "\"" represents a quote within a string. Some
other C escape sequences are allowed but are not supported. Arbitrary ascii
codes might be included by "\nnn", where nnn is a 3-digit number in
octal notation (for example, "\012" denotes "\n").
Value
| character | returns a character vector of the
length specified containing null strings (""). |
| is.character | returns TRUE if x has mode
"character". Otherwise, it returns FALSE.
Its behavior is unaffected by any attributes of x. For example, this function
returns TRUE if x is a character array (in contrast to the behavior
of is.vector). |
| as.character | returns x if x is a simple
object of mode "character". Otherwise, it returns a character vector
of the same length as x, with data resulting from coercing the
elements of x to mode "character". |
See Also
Examples
character(5) # a character object with length 5: "", "", "", "",""
as.character(1:10) # character representations of 1,2,...,10
x <- matrix(c("a","b","c","d"), 2)
is.character(x)
# TRUE, since the mode of x is character though its class is matrix
as.character(x) # "a","b","c","d"
x <- factor(c("a","b","c","a")) # Examples for a factor
is.character(x) # FALSE, since the mode of x is numeric for a factor
as.character(x) # "a","b","c","a"
x <- ordered(c("a","b","c","a")) # Examples for an ordered factor
is.character(x)
# FALSE, since the mode of x is numeric for an ordered factor
as.character(x) # "a","b","c","a"