生信人的R语言视频教程-语法篇-第十二章：面向对象编程(S3类与S4类）

stringAsFactors=FALSE
#创建一个S3类
me = list(name = "DoubleHelix",Age = 27,Gender = "male")
me
me[["Major"]] <- "bioinformatics"
me
#S3类可以通过$来访问类的属性
me$name
class(me)

class(me) <- append(class(me),"Person")
class(me)
me

Person <- function(name,age,Gender){
  name = name
  age = age
  Genter = Gender
  aPerson = list(name,age,Genter)# 给类取名
  class(aPerson) = append(class(aPerson),"Person")
  return(aPerson)
}

Person1 <- Person(name = "Darren",age = 18,Gender = "Man")
Person5 <- Person(name = "zhangsan",age = 16,Gender = "Man")
class(Person1)

student <- function(name,age,Gender,ID){
  student = Person(name,age,Gender)
  student$ID = ID
  class(student) <- append(class(student), "student") 
  return(student)
}

Person2 <- student(name = "Alis",age = 20,Gender = "woman",ID = "2020090418")
class(Person2)

# 泛型函数
x <- 1:20
y <- 1:20 + rnorm(20)
plot(x,y)
fit <- lm(y~x)
plot(fit, 1)
class(fit)
methods(plot)

#创建泛型函数
speak <- function(object){
  UseMethod("speak", object)
}
speak.default <- function(object){
  print("正常人都具有说话的功能")
}
speak(Person2)
speak.student<- function(object){
  print("我是学生，我具有学习的能力")
}
speak(Person2)

###---------------------S4类-------------------
# setClass(Class, representation, prototype, contains=character(), 
#          validity, access, where, version, sealed, package,  
#          S3methods = FALSE, slots)
#Class：定义的类名
#slots：定义类的属性
#prototype：定义属性的默认值（这个有什么用，我还没有发掘）
#contains = character()：定义父类和继承关系
#where：定义存储空间
#sealed：若是TRUE，则同类名不能被定义
#package：定义所属包

setClass("Person", slots = list(name="character",age="numeric"))

#实例化一个人,也就是创建一个对象
Person3 <- new("Person",name="potter",age=49) 
Person3

#创建一个子类
setClass("Student",slots = list(ID="character",school= "character"),
         contains = "Person")#contain表明类的继承关系，继承自Person
#实例化类
Person3 <- new("Person",name="potter",age=49)

Student1 <- new("Student",name="liming",age=16,ID="2020051419",school="Taiwan University")

Student1

Student1@name
Student1@school

work<-function(x) cat(x, "is working")
work('Conan')
# 定义Person对象
setClass("Person",slots=list(name="character",age="numeric"))
# 定义泛型函数work，即接口
setGeneric("work",function(object) standardGeneric("work"))
# 定义work的实现，并指定参数类型为Person对象
setMethod("work", signature(object = "Person"), function(object) cat(object@name , "is working") )
# 创建一个Person对象a
a<-new("Person",name="Conan",age=16)
# 把对象a传入work函数
work(a)
# 检查work的类型
class(work)
# 直接查看work函数
work
# 查看work函数的现实定义
showMethods(work)
# 查看Person对象的work函数现实
getMethod("work", "Person")
selectMethod("work", "Person")
# 检查Person对象有没有work函数
existsMethod("work", "Person")
hasMethod("work", "Person")