R语言基础（二）

对象

1. 数据的类型与结构

1.1 数据的结构

1.2 原子数据的类型
atomic vector包括 char\ integer\ double\ logical\ complex\ raw.

2. 数据的属性

2.1 Property（属性）的定义

atomic vector and list have 3 common properties: type length and attributes.

Type, typeof(), what it is.

Length, length(), how many elements it contains.

Attributes,attributes(), additional arbitrary metadata.

2.2 three most important Attributes

Names, a character vector giving each element a name.

Dimensions, used to turn vectors into matrices and arrays.

Class, used to implement the S3 object system.

PS: 对象（object）的界面（interface）就是属性（properties）和方法（method）。
来自《自学是门手艺--class》