訊息
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向量
> x = 2:9
> x
[1] 2 3 4 5 6 7 8 9
> x+1
[1] 3 4 5 6 7 8 9 10
> x-2.1
[1] -0.1 0.9 1.9 2.9 3.9 4.9 5.9 6.9
> x*5
[1] 10 15 20 25 30 35 40 45
> x*x
[1] 4 9 16 25 36 49 64 81
> y=2*x
> x*y
[1] 8 18 32 50 72 98 128 162
> y-x
[1] 2 3 4 5 6 7 8 9
> z = c(1,2,3,4)
> z^z
[1] 1 4 27 256
> cos(x*pi)
[1] 1 -1 1 -1 1 -1 1 -1
> cos(0.5*x*pi)
[1] -1.000000e+00 -1.836910e-16 1.000000e+00 3.061516e-
16 -1.000000e+00
[6] -4.286122e-16 1.000000e+00 5.510729e-16
> length(x)
[1] 8
> sum(x)
[1] 44
> prod(x)
[1] 362880
> cumsum(x)
[1] 2 5 9 14 20 27 35 44
> x = c(3, "abc", 4)
> x
[1] "3" "abc" "4"
> w = c(x,y)
> w
[1] "3" "abc" "4" "4" "6" "8" "10" "12" "14"
"16" "18"
>
> x = 1:5
> length(x)
[1] 5
> y=1:12
> y
[1] 1 2 3 4 5 6 7 8 9 10 11 12
> matrix(y, 3,4)
[,1] [,2] [,3] [,4]
[1,] 1 4 7 10
[2,] 2 5 8 11
[3,] 3 6 9 12
> dim(x)
NULL
> dim(y)
NULL
> dim x
錯誤: unexpected symbol in "dim x"
> w = matrix(y, 3,4)
> dim(w)
[1] 3 4
> x
[1] 1 2 3 4 5
> x=x[-c(2,4)]
> x
[1] 1 3 5
> y
[1] 1 2 3 4 5 6 7 8 9 10 11 12
> y[c(2,3,4)]=c(12,13,14)
> y
[1] 1 12 13 14 5 6 7 8 9 10 11 12
> x
[1] 1 3 5
>
> x=3:7
> x
[1] 3 4 5 6 7
> y=c(n1=1, n2=2, n3=3)
> y
n1 n2 n3
1 2 3
> y[c(n1,n3)]
錯誤: 找不到目的物件 'n1'
> y[c("n1","n3")]
n1 n3
1 3
> y[c(1,3)]
n1 n3
1 3
> z=c(一=1, 二=2, 三=3)
> z
一 二 三
1 2 3
> names(z)
[1] "一" "二" "三"
> w = 3:5
> w
[1] 3 4 5
> names(v) = c("叁", "肆", "伍"); w
錯誤在names(v) = c("<U+53C1>", "肆", "伍") : 找不到目的物件 'v'
> names(w) = c("叁", "肆", "伍"); w
叁 肆 伍
3 4 5
向量索引
> x = c(3,5,9)
> x[2]
[1] 5
> x
[1] 3 5 9
> x[c(1,3)]
[1] 3 9
> x[c(3)]
[1] 9
> x[1:2]
[1] 3 5
> y=x[1:2]
> y
[1] 3 5
>
> x=1:4
> y=5:8
> xy=rbind(x,y)
> x
[1] 1 2 3 4
> y
[1] 5 6 7 8
> xy
[,1] [,2] [,3] [,4]
x 1 2 3 4
y 5 6 7 8
> xyc = cbind(x,y)
> xyc
x y
[1,] 1 5
[2,] 2 6
[3,] 3 7
[4,] 4 8
> is.array(xy)
[1] TRUE
> is.array(x)
[1] FALSE
> is.matrix(xy)
[1] TRUE
> is.matrix(x)
[1] FALSE
> x=array(1:12, dim=c(3,4))
> x
[,1] [,2] [,3] [,4]
[1,] 1 4 7 10
[2,] 2 5 8 11
[3,] 3 6 9 12
> length(x)
[1] 12
> nrow(x)
[1] 3
> ncol(x)
[1] 4
> x[1,]
[1] 1 4 7 10
> x[,2]
[1] 4 5 6
> x[1,2]
[1] 4
> y=x[1, c(2,3)]
> y
[1] 4 7
> z=x(c(1,2))
錯誤: 沒有這個函數 "x"
> z=x[c(1,2)]
> z
[1] 1 2
> z=x[c(10,11)]
> z
[1] 10 11
> x
[,1] [,2] [,3] [,4]
[1,] 1 4 7 10
[2,] 2 5 8 11
[3,] 3 6 9 12
> x[2:3, 2:3]
[,1] [,2]
[1,] 5 8
[2,] 6 9
>
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