Summary
attributes, attr, class, methods, UseMethod, getAnywhere
attributes
Print attributes of an object.
attr
change attributes of an object.
class
change class of an object.
methods
Print methods in a generic function.
UseMethod
Constructing a generic function.
GF <- function(x, ...) UseMethod('GF')
getAnywhere
find a function
Examples
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | #------------- Create a generic method> whoami <- function(x, ...) UseMethod("whoami")> whoami.foo <- function(x) print("I am a foo")> whoami.bar <- function(x) print("I am a bar")> whoami.default <- function(x) print("I don't know who I am")> a = 1:10> b = 2:20> whoami(a) # No class assigned[1] "I don't know who I am"> attr(a,'class') <- 'foo'> attr(b,'class') <- c('baz','bam','bar')> whoami(a)[1] "I am a foo"> whoami(b) # Search MRO for defined method[1] "I am a bar"> attr(a,'class') <- 'bar' # Change the class of 'a'> whoami(a)[1] "I am a bar" |
Golden rule
- eveything is an object, a vector
- DO NOT call methods directly, instead use a generic function, which dispatches methods to objects according to their classes.
Concepts
-
Inheritance: A way to form new classes using classes that have already been defined.
class(x) = c('newClass', class(x))
References
http://www.ibm.com/developerworks/linux/library/l-r3/index.html#N10139 http://brainimaging.waisman.wisc.edu/~perlman/R/A1%20Introduction%20to%20object-oriented%20programming.pdf
Hide Comments