R:什么是老虎机? [英] R: what are Slots?

问题描述

有人知道R中的插槽吗?

Does anyone know what a slot is in R?

我没有找到其含义的解释.我得到一个递归定义: 插槽功能返回或设置有关对象各个插槽的信息"

I did not find the explanation of its meaning. I get a recursive definition: "Slot function returns or set information about the individual slots of an objects"

我们将不胜感激， 谢谢 - 胡同

Help would be appreciated, Thanks - Alley

推荐答案

插槽已链接到S4对象.插槽可以看作是对象的一部分，元素或属性".假设您有一个汽车物体，那么您可以拥有价格"，门数"，发动机类型"，里程"等插槽.

Slots are linked to S4 objects. A slot can be seen as a part, element or a "property" of an object. Say you have a car object, then you can have the slots "price", "number of doors", "type of engine", "mileage".

在内部，它表示一个列表.一个例子:

Internally, that is represented a list. An example :

setClass("Car",representation=representation(
   price = "numeric",
   numberDoors="numeric",
   typeEngine="character",
   mileage="numeric"
))
aCar <- new("Car",price=20000,numberDoors=4,typeEngine="V6",mileage=143)

> aCar
An object of class "Car"
Slot "price":
[1] 20000

Slot "numberDoors":
[1] 4

Slot "typeEngine":
[1] "V6"

Slot "mileage":
[1] 143

此处，价格，门数，类型发动机和里程数是S4类汽车"的插槽.这是一个简单的例子，实际上插槽本身又可以是复杂的对象.

Here, price, numberDoors, typeEngine and mileage are slots of the S4 class "Car". This is a trivial example, in reality slots themselves can be again complex objects.

可以通过多种方式访问​​插槽:

Slots can be accessed in numerous ways :

> aCar@price
[1] 20000
> slot(aCar,"typeEngine")
[1] "V6"    

或通过构造特定方法(请参阅其他文档).

or through the construction of a specific method (see extra documentation).

有关S4编程的更多信息，请参见此问题.如果您仍然对这个概念感到困惑，那么对面向对象编程的一般介绍可能会有所帮助.

For more on S4 programming see this question. If the concept still sounds vague to you, a general introduction in Object Oriented Programming could help.

PS:请注意数据框和列表的区别，在其中使用$访问命名变量/元素.

PS: Mind the difference with dataframes and lists, where you use $ to access named variables/elements.

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