变量不需要声明，
常用的变量有：
| 变量类型 | 定义 | 例子 | 例子效果 |
| logical | 逻辑型：TRUE , FALSE | v<-TRUE; print(class(v)) | "logical" |
| numeric | 数字型：23.4, 2 , | v<-23.5;print(class(v)) | "numeric" |
| integer | 整型：2L, 0L | v<-2L;print(class(v)) | "numeric" |
| complex | 复合型 | v<-3+2i;print(class(v)) | "complex" |
| character | 字符型：'a',"FALSE" | v<-"TRUE";print(class(v)) | "character" |
| raw | 原型："Hello" 被存储为 48 65 6c 6c 6f | v<-charToRaw("Hello"); print(class(v)); print(v) | [1] "raw" [1] 48 65 6c 6c 6f |
| vectors | apple<-c("red","green"); print(apple); print(class(apple)) | [1] "red" "green" [1] "character" | |
| list | 列表型 | list1<-list(c(2,5,3),21.3,sin)；print(list1); print(class(list1)) | [[1]] [1] 2 5 3[[2]] [1] 21.3[[3]] function (x) .Primitive("sin")################ [1] "list" |
| Matrices | 矩阵型 | M=matrix(c('a','a','b'),nrow=2,ncol=3,byrow=TRUE); print(M) | [,1] [,2] [,3] [1,] "a" "a" "b" [2,] "a" "a" "b" |
| array | 数组型 | #包含两个元素的数组，每个元素为2x3个矩阵 a <- array(c('green','yellow','e'),dim = c(2,3,2)); print(a)
| , , 1 [,1] [,2] [,3] [1,] "green" "green" "green" [2,] "yellow" "yellow" "yellow", , 2 [,1] [,2] [,3] [1,] "green" "green" "green" [2,] "yellow" "yellow" "yellow" |
| factor | 因子： 它将向量与向量中元素的不同值一起存储为标签。 标签总是字符， 不管它在输入向量中是数字还是字符或布尔等。 | apple_colors<-c('green','green','yellow','red'); factor_apple<-factor(apple_colors);print(factor_apple);print(class(factor_apple));print(nlevels(factor_apple)) | [1] green green yellow red Levels: green red yellow[1] "factor"[1] 3 |
| data.frame | 数据帧：表格数据对象 | BMI <- data.frame( gender = c("Male", "Male","Female"), height = c(152, 171.5, 165), weight = c(81,93, 78), Age = c(42,38,26))print(BMI) | gender height weight Age 1 Male 152.0 81 422 Male 171.5 93 383 Female 165.0 78 26 |