R语言属性知识点总结及实例

m = matrix(data = 1:12, nrow = 4, ncol = 3,
      dimnames = list(c("r1", "r2", "r3", "r4"),
              c("c1", "c2", "c3")))

> attributes(m)
$dim
[1] 4 3

$dimnames
$dimnames[[1]]
[1] "r1" "r2" "r3" "r4"

$dimnames[[2]]
[1] "c1" "c2" "c3"

> dim(m)
[1] 4 3
> dimnames(m)
[[1]]
[1] "r1" "r2" "r3" "r4"

[[2]]
[1] "c1" "c2" "c3"

> colnames(m)
[1] "c1" "c2" "c3"
> rownames(m)
[1] "r1" "r2" "r3" "r4"

> dim(m) <- NULL
> m
 [1] 1 2 3 4 5 6 7 8 9 10 11 12
 > class(m)
[1] "integer"
> typeof(m)
[1] "integer"

> (a <- array(1:12, dim = c(3:4)))
   [,1] [,2] [,3] [,4]
[1,]  1  4  7  10
[2,]  2  5  8  11
[3,]  3  6  9  12

> (b <- 1:12)
 [1] 1 2 3 4 5 6 7 8 9 10 11 12

> a == b
   [,1] [,2] [,3] [,4]
[1,] TRUE TRUE TRUE TRUE
[2,] TRUE TRUE TRUE TRUE
[3,] TRUE TRUE TRUE TRUE

> all.equal(a, b)
[1] "Attributes: < Modes: list, NULL >"          "Attributes: < Lengths: 1, 0 >"            
[3] "Attributes: < names for target but not for current >" "Attributes: < current is not list-like >"      
[5] "target is matrix, current is numeric" 

> identical(a, b)
[1] FALSE

> (eye.colors <- factor(c("brown", "blue", "blue", "green", "brown", "brown", "brown")))
[1] brown blue blue green brown brown brown
Levels: blue brown green
> (eye.colors.integer.vector <- unclass(eye.colors))
[1] 2 1 1 3 2 2 2
attr(,"levels")
[1] "blue" "brown" "green"

> v <- as.integer(c(1, 1, 1, 2, 1, 1, 2, 2, 3, 1))
> levels(v) <- c("what", "who", "why")
> class(v) <- "factor"
> v
 [1] what what what who what what who who why what
Levels: what who why

> class(quote(v))
[1] "name"
> typeof(quote(v))
[1] "symbol"