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How to merge two matrices by combining rows in R?
By combining rows means that we want to concatenate rows of matrices but create separate columns as in the original matrices. For example, if we have two matrices say M1 and M2 as shown below −
M1 1 2 3 3 2 1 M2 2 3 5 1 2 3
Then merging of these two matrices by combining rows will result in −
1 2 3 2 3 5 3 2 1 1 2 3
Example1
> M1<-matrix(rpois(40,5),nrow=20) > M1
Output
[,1] [,2] [1,] 5 2 [2,] 7 4 [3,] 3 6 [4,] 7 7 [5,] 5 3 [6,] 2 7 [7,] 4 7 [8,] 10 7 [9,] 7 2 [10,] 2 4 [11,] 7 5 [12,] 1 6 [13,] 2 3 [14,] 4 6 [15,] 7 6 [16,] 5 7 [17,] 3 2 [18,] 7 4 [19,] 9 6 [20,] 5 6
Example
> M2<-matrix(rpois(40,5),nrow=20) > M2
Output
[,1] [,2] [1,] 4 7 [2,] 2 9 [3,] 5 3 [4,] 2 10 [5,] 5 2 [6,] 5 5 [7,] 3 7 [8,] 6 5 [9,] 4 4 [10,] 5 0 [11,] 3 3 [12,] 5 2 [13,] 3 8 [14,] 2 6 [15,] 2 4 [16,] 10 5 [17,] 5 8 [18,] 1 4 [19,] 6 6 [20,] 4 6
Merging M1 and M2 by rows −
> merge(M1,M2,by="row.names",all=TRUE)
Output
Row.names V1.x V2.x V1.y V2.y 1 1 5 2 4 7 2 10 2 4 5 0 3 11 7 5 3 3 4 12 1 6 5 2 5 13 2 3 3 8 6 14 4 6 2 6 7 15 7 6 2 4 8 16 5 7 10 5 9 17 3 2 5 8 10 18 7 4 1 4 11 19 9 6 6 6 12 2 7 4 2 9 13 20 5 6 4 6 14 3 3 6 5 3 15 4 7 7 2 10 16 5 5 3 5 2 17 6 2 7 5 5 18 7 4 7 3 7 19 8 10 7 6 5 20 9 7 2 4 4
Example2
> M3<-matrix(rpois(40,1),nrow=20) > M3
Output
[,1] [,2] [1,] 0 1 [2,] 0 1 [3,] 3 0 [4,] 2 0 [5,] 0 1 [6,] 2 1 [7,] 1 0 [8,] 2 0 [9,] 2 1 [10,] 0 1 [11,] 3 0 [12,] 2 0 [13,] 2 0 [14,] 1 2 [15,] 1 2 [16,] 0 1 [17,] 4 1 [18,] 1 1 [19,] 1 2 [20,] 1 1
Example
> M4<-matrix(rpois(40,1),nrow=20) > M4
Output
[,1] [,2] [1,] 1 0 [2,] 2 2 [3,] 1 0 [4,] 1 0 [5,] 0 2 [6,] 1 1 [7,] 2 0 [8,] 2 1 [9,] 0 0 [10,] 0 1 [11,] 3 0 [12,] 3 2 [13,] 3 5 [14,] 0 0 [15,] 2 1 [16,] 0 0 [17,] 1 1 [18,] 0 0 [19,] 1 1 [20,] 1 2
Merging M3 and M4 by rows −
> merge(M3,M4,by="row.names",all=TRUE)
Output
Row.names V1.x V2.x V1.y V2.y 1 1 0 1 1 0 2 10 0 1 0 1 3 11 3 0 3 0 4 12 2 0 3 2 5 13 2 0 3 5 6 14 1 2 0 0 7 15 1 2 2 1 8 16 0 1 0 0 9 17 4 1 1 1 10 18 1 1 0 0 11 19 1 2 1 1 12 2 0 1 2 2 13 20 1 1 1 2 14 3 3 0 1 0 15 4 2 0 1 0 16 5 0 1 0 2 17 6 2 1 1 1 18 7 1 0 2 0 19 8 2 0 2 1 20 9 2 1 0 0
Updated on: 04-Mar-2021
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