Question

如何创建一个将数组作为插槽的S4类？下面，我有一个示例类。我希望能够以这样一种方式构造，即我得到两个“人”元素，每个元素都有适当的数组成员。

下面的代码给出了以下错误：“validObject（.Object）中的错误：无效的类“人”对象：类“人”中的插槽“子”的无效对象：得到类“字符”，应该是或扩展类“数组”

setClass("person", representation(name="character", age="numeric", children = "array"))

setMethod(
  f = "[",
  signature="person",
  definition=function(x,i,j,...,drop=TRUE){ 
    initialize(x, name=x@name[i], age = x@age[i], children = x@children[i])
  }
)

setMethod(f = "length", signature = "person", definition = function(x){
  length(x@name)
})

setMethod(f = "dim", signature = "person", definition = function(x){
  length(x@name)
})

kids1 = as.array(c("Bob", "Joe", "Mary"))

person = new("person", name="John", age=40, children = kids1)

person@children[2]

kids2 = as.array(c("Steve", "Beth", "Kim"))

people = new("person", name=c("John", "Fred"), age=c(40, 20), children = as.array(c(kids1, kids2), dim = 2))

people[1]@age
people[2]@children[1]

Answer 1

您可能不希望@children成为数组。如果dim属性长度为1，则它与向量基本相同，并且您无法区分不同人的孩子。考虑将此插槽改为列表。

setClass("person",
    representation(name="character", age="numeric", children = "list"))

person = new("person", name="John", age=40, children = list(kids1))
person@children

people = new("person", name=c("John", "Fred"), age=c(40, 20),
             children = list(kids1, kids2))
people[1]

Answer 2

将drop=FALSE添加到children广告位的子集中;这是数组子集的标准R规则的结果

setMethod(
  f = "[",
  signature="person",
  definition=function(x,i,j,...,drop=TRUE){ 
    initialize(x, name=x@name[i], age = x@age[i], 
      children = x@children[i,drop=FALSE])
  }
)

另外，我不确定你的as.array()是按照你的想法做的？ dim参数被忽略。

Answer 3

Hong的回答有效。我确实需要在“[”子集函数中添加一个列表包装器。一旦完成，一切正常。

kids1 = as.array(c("Bob", "Joe"))
kids2 = as.array(c("Steve", "Beth", "Kim"))

setClass("person", representation(name="character", age="numeric", children = "list"))

setMethod(
  f = "[",
  signature="person",
  definition=function(x,i,j,...,drop=TRUE){ 
    initialize(x, name=x@name[i], age = x@age[i], children = list(x@children[i]))
  }
)

people = new("person", name=c("John", "Fred"), age=c(40, 20), children = list(kids1, kids2))

people[1]@name
people[1]@age
people[1]@children

people[2]@name
people[2]@age
people[2]@children

如何创建一个包含包含数组的插槽的S4阵列

3 个答案: