| class {base} | R Documentation |
R possesses a simple generic function mechanism which can be used for an object-oriented style of programming. Method despatch takes place based on the class of the first argument to the generic function.
class(x)
class(x) <- names
unclass(x)
inherits(x, what, which = FALSE)
x |
an objects |
what |
a character vector naming classes. |
which |
logical affecting return value: see Details. |
An R “object” is a data object which has a class attribute.
A class attribute is a character vector giving the names of
the classes which the object “inherits” from. When a generic
function fun is applied to an object with class attribute
c("first", "second"), the system searches for a function called
fun.first and, if it finds it, applies it to the object. If no
such function is found, a function called fun.second is tried.
If no class name produces a suitable function, the function
fun.default is used.
The function class prints the vector of names of classes an
object inherits from. Correspondingly, class<- sets the
classes an object inherits from.
unclass returns (a copy of) its argument with its class
information removed.
inherits indicates whether its first argument inherits from any
of the classes specified in the what argument. If which
is TRUE then an integer vector of the same length as
what is returned. Each element indicates the position in the
class(x) matched by the element of what; zero indicates
no match. If which is FALSE then TRUE is
returned by inherits if any of the names in what match
with any class.
UseMethod, NextMethod.
x <- 10
inherits(x, "a") #FALSE
class(x)<-c("a", "b")
inherits(x,"a") #TRUE
inherits(x, "a", TRUE) # 1
inherits(x, c("a", "b", "c"), TRUE) # 1 2 0