How to change the repeated row names and column names to a sequence in a matrix in R?

To change the repeated row names and column names to a sequence, we first need to read those names in a vector then set them to row names and column names with make.unique function. For example, if a matrix has row names defined as A, B, A, B, A then it can be converted into A, B, A.1, B.1, A.2.

Example1

 Live Demo

M1<−matrix(1:25,ncol=5)
M1

Output

   [,1] [,2] [,3] [,4] [,5]
[1,] 1    6   11   16   21
[2,] 2    7   12   17   22
[3,] 3    8   13   18   23
[4,] 4    9   14   19   24
[5,] 5   10   15   20   25

Example

colnames(M1)<−c("A","B","A","A","B")
rownames(M1)<−c("C","D","D","C","C")
M1

Output

  A B A  A  B
C 1 6 11 16 21
D 2 7 12 17 22
D 3 8 13 18 23
C 4 9 14 19 24
C 5 10 15 20 25

Example

C1<−c("A","B","A","A","B")
colnames(M1)<−make.unique(C1)
R1<−c("C","D","D","C","C")
rownames(M1)<−make.unique(R1)
M1

Output

  A B A.1 A.2 B.1
C 1 6 11 16   21
D 2 7 12 17   22
D.1 3  8 13   18 23
C.1 4  9 14   19 24
C.2 5 10 15   20 25

Example2

 Live Demo

M2<−matrix(rnorm(25),nrow=5)
M2

Output

      [,1]          [,2]       [,3]       [,4]       [,5]
[1,] −0.9603079 2.7738930 −1.68887845 −0.3516074 2.237315508
[2,] −0.3346606 −1.2140159 −0.08791009 −0.3596462 −0.009851671
[3,] 0.7399818 −2.1791770 −1.70416955 0.2715390 −0.766143519
[4,] 1.1195890 −1.7790965 0.09878024 −0.4761445 1.859189587
[5,] −1.3238430 0.2936939 −2.15993049 −0.9182923 −0.647121554

Example

colnames(M2)<−c("Hot","Cold","Cold","Hot","Hot")
rownames(M2)<−c("Asian","Americas","Americas","Asian","Americas")
M2

Output

Hot Cold Cold Hot Hot
Asian −0.9603079 2.7738930 −1.68887845 −0.3516074 2.237315508
Americas −0.3346606 −1.2140159 −0.08791009 −0.3596462 −0.009851671
Americas 0.7399818 −2.1791770 −1.70416955 0.2715390 −0.766143519
Asian 1.1195890 −1.7790965 0.09878024 −0.4761445 1.859189587
Americas −1.3238430 0.2936939 −2.15993049 −0.9182923 −0.647121554

Example

C2<−c("Hot","Cold","Cold","Hot","Hot")
colnames(M2)<−make.unique(C2)
R2<−c("Asian","Americas","Americas","Asian","Americas")
rownames(M2)<−make.unique(R2)
M2

Output

Hot Cold Cold.1 Hot.1 Hot.2
Asian −0.9603079 2.7738930 −1.68887845 −0.3516074 2.237315508
Americas −0.3346606 −1.2140159 −0.08791009 −0.3596462 −0.009851671
Americas.1 0.7399818 −2.1791770 −1.70416955 0.2715390 −0.766143519
Asian.1 1.1195890 −1.7790965 0.09878024 −0.4761445 1.859189587
Americas.2 −1.3238430 0.2936939 −2.15993049 −0.9182923 −0.647121554

Example3

 Live Demo

M3<−matrix(sample(c(21:50),16),nrow=4)
M3

Output

   [,1] [,2] [,3] [,4]
[1,] 36  46   26   21
[2,] 42  24   34   50
[3,] 37  33   43   27
[4,] 45  30   49   39

Example

colnames(M3)<−c("V1","V1","V2","V2")
rownames(M3)<−c("case1","case2","case2","case1")
M3

Output

      V1 V1 V2 V2
case1 36 46 26 21
case2 42 24 34 50
case2 37 33 43 27
case1 45 30 49 39

Example

C3<−c("V1","V1","V2","V2")
colnames(M3)<−make.unique(C3)
R3<−c("case1","case2","case2","case1")
rownames(M3)<−make.unique(R3)
M3

Output

     V1 V1.1 V2 V2.1
case1 36 46 26 21
case2 42 24 34 50
case2.1 37 33 43 27
case1.1 45 30 49 39

Nizamuddin Siddiqui

Updated on: 05-Feb-2021

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