R语言的使用——笔记1

基本数据操作

>x1 = c(171, 175, 159, 155, 152, 158)
>x1
[1] 171 175 159 155 152 158
>x2 = c(57, 64, 41, 38, 35, 44); x2
[2] 57 64 41 38 35 44
>rbind(x1, x2) #按行合并
   [,1] [,2] [,3] [,4] [,5] [,6]
x1  171  175  159  155  152  158
x2   57   64   41   38   35   44
>cbind(x1, x2) #按列合并
      x1 x2
[1,] 171 57
[2,] 175 64
[3,] 159 41
[4,] 155 38
[5,] 152 35
[6,] 158 44
#利用x1数据创建矩阵
>matrix(x1, nrow = 3, ncol = 2)
     [,1] [,2]
[1,]  171  155
[2,]  175  152
[3,]  159  158
#创建两个相同的矩阵
> A = B = matrix(1 : 12, nrow = 3, ncol = 4)
> A + B #矩阵加法
     [,1] [,2] [,3] [,4]
[1,]    2    8   14   20
[2,]    4   10   16   22
[3,]    6   12   18   24
> A - B #矩阵减法
     [,1] [,2] [,3] [,4]
[1,]    0    0    0    0
[2,]    0    0    0    0
[3,]    0    0    0    0
> A = matrix(1 : 9, nrow = 3, ncol = 3)
> B = matrix(1 : 9, nrow = 3, ncol = 3)
> A * B #矩阵对应元素的乘积
     [,1] [,2] [,3]
[1,]    1   16   49
[2,]    4   25   64
[3,]    9   36   81
> A %*% B #矩阵的乘积
     [,1] [,2] [,3]
[1,]   30   66  102
[2,]   36   81  126
[3,]   42   96  150
> A = matrix(1 : 16, nrow = 4, ncol = 4)
> diag(A) #获得矩阵对角线元素
[1]  1  6 11 16
> diag(diag(A)) #利用对角线元素创建对角矩阵
     [,1] [,2] [,3] [,4]
[1,]    1    0    0    0
[2,]    0    6    0    0
[3,]    0    0   11    0
[4,]    0    0    0   16
> A = matrix(rnorm(16), 4, 4)
> solve(A) #求矩阵的逆
            [,1]       [,2]       [,3]      [,4]
[1,] -0.39956043 -0.2815026  0.8999073 -2.145375
[2,] -0.02913893  0.4045662 -0.9829441  1.023210
[3,]  0.49204662  0.1090693  1.6045602 -2.799157
[4,]  0.14880767  0.4904336 -0.3088533  1.473945
> A = diag(4) + 1
> A.e = eigen(A, symmetric = T)
> A.e #求特征根和特征向量
eigen() decomposition
$values
[1] 5 1 1 1

$vectors
     [,1]       [,2]       [,3]       [,4]
[1,] -0.5  0.8660254  0.0000000  0.0000000
[2,] -0.5 -0.2886751 -0.5773503 -0.5773503
[3,] -0.5 -0.2886751 -0.2113249  0.7886751
[4,] -0.5 -0.2886751  0.7886751 -0.2113249