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法律研究如何在R语言中使用行名创建矩阵的子集？
在R语言中创建矩阵时，行名和列名未定义，但我们可以分别定义它们。如果我们想获取矩阵的行子集，可以使用单方括号中的行号；但如果我们想用名称来获取子集，则需要指定这些名称。
示例
M1<-matrix(1:25,ncol=5) rownames(M1)<-letters[1:5] M1
输出
[,1] [,2] [,3] [,4] [,5] a 1 6 11 16 21 b 2 7 12 17 22 c 3 8 13 18 23 d 4 9 14 19 25
示例
M1[c("a","b"),]输出
[,1] [,2] [,3] [,4] [,5] a 1 6 11 16 21 b 2 7 12 17 22
示例
M1[c("a","d"),]输出
[,1] [,2] [,3] [,4] [,5] a 1 6 11 16 21 d 4 9 14 19 24
示例
M1[c("a","e"),]输出
[,1] [,2] [,3] [,4] [,5] a 1 6 11 16 21 e 5 10 15 20 25
示例
M1[c("a","b","e"),]输出
[,1] [,2] [,3] [,4] [,5] a 1 6 11 16 21 b 2 7 12 17 22 e 5 10 15 20 25
示例
M1[c("a","b","d","e"),]输出
[,1] [,2] [,3] [,4] [,5] a 1 6 11 16 21 b 2 7 12 17 22 d 4 9 14 19 24 e 5 10 15 20 25
示例
M2<-matrix(1:100,nrow=10) rownames(M2)<-LETTERS[1:10] M2
输出
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] A 1 11 21 31 41 51 61 71 81 91 B 2 12 22 32 42 52 62 72 82 92 C 3 13 23 33 43 53 63 73 83 93 D 4 14 24 34 44 54 64 74 84 94 E 5 15 25 35 45 55 65 75 85 95 F 6 16 26 36 46 56 66 76 86 96 G 7 17 27 37 47 57 67 77 87 97 H 8 18 28 38 48 58 68 78 88 98 I 9 19 29 39 49 59 69 79 89 99 J 10 20 30 40 50 60 70 80 90 100
示例
M2[c("A","J"),]输出
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] A 1 11 21 31 41 51 61 71 81 91 J 10 20 30 40 50 60 70 80 90 100
示例
M2[c("A","D","F","I"),]输出
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] A 1 11 21 31 41 51 61 71 81 91 D 4 14 24 34 44 54 64 74 84 94 F 6 16 26 36 46 56 66 76 86 96 I 9 19 29 39 49 59 69 79 89 99
示例
M2[c("A","C","E","G","J"),]输出
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] A 1 11 21 31 41 51 61 71 81 91 C 3 13 23 33 43 53 63 73 83 93 E 5 15 25 35 45 55 65 75 85 95 G 7 17 27 37 47 57 67 77 87 97 J 10 20 30 40 50 60 70 80 90 100
示例
M3<-matrix(rnorm(25,1,0.04),nrow=5)
rownames(M3)<-c("Rate1","Rate2","Rate3","Rate4","Rate5")
M3输出
[,1] [,2] [,3] [,4] [,5] Rate1 1.0095550 0.9804156 0.9655588 1.025432 0.9420430 Rate2 0.9926681 0.9830571 0.9428085 1.000219 0.9980977 Rate3 1.0039020 1.0121637 1.0291146 1.062020 1.0822971 Rate4 1.0720653 1.0469583 0.9947673 1.065848 1.0165283 Rate5 0.9752784 1.0382877 0.9933063 1.011313 0.9942537
示例
M3["Rate3",]
输出
[1] 1.003902 1.012164 1.029115 1.062020 1.082297
示例
M3[c("Rate1","Rate5"),]输出
[,1] [,2] [,3] [,4] [,5] Rate1 1.0095550 0.9804156 0.9655588 1.025432 0.9420430 Rate5 0.9752784 1.0382877 0.9933063 1.011313 0.9942537
示例
M3[c("Rate1","Rate3","Rate5"),]输出
[,1] [,2] [,3] [,4] [,5] Rate1 1.0095550 0.9804156 0.9655588 1.025432 0.9420430 Rate3 1.0039020 1.0121637 1.0291146 1.062020 1.0822971 Rate5 0.9752784 1.0382877 0.9933063 1.011313 0.9942537
更新于：2020年10月18日
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