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Create a matrix for odd number of elements by filling the last element with NA in R.
We can find the total number of elements for a matrix with the help of prod and dim function as shown in the below Examples. To create a matrix for odd number of elements by filling the last element with NA, we can use byrow argument.
For Example, if we have a vector called V that contains 19 elements then we can create a matrix called M having 20 elements NA as the last element by using the below command −
M<-matrix(V,ncol=2,byrow=TRUE)
Example 1
Consider the vector given below −
x1<-rpois(39,5) length(x1)<-prod(dim(matrix(x1,ncol=2)))
Warning message
In matrix(x1, ncol = 2) : data length [39] is not a sub-multiple or multiple of the number of rows [20]
To create matrix of x1 on the above created matrix, add the following code to the above snippet −
M1<-matrix(x1,ncol=2,byrow=TRUE) M1
The following matrix is created −
[,1] [,2] [1,] 2 5 [2,] 10 3 [3,] 3 5 [4,] 5 5 [5,] 5 5 [6,] 4 3 [7,] 2 3 [8,] 5 4 [9,] 6 6 [10,] 5 4 [11,] 6 3 [12,] 3 6 [13,] 6 4 [14,] 4 7 [15,] 7 5 [16,] 1 4 [17,] 3 4 [18,] 6 5 [19,] 4 6 [20,] 2 NA
Example 2
Consider the vector given below −
x2<-rnorm(39) length(x2)<-prod(dim(matrix(x2,ncol=2)))
Warning message
In matrix(x2, ncol = 2) : data length [39] is not a sub-multiple or multiple of the number of rows [20]
To create matrix of x2 on the above created matrix, add the following code to the above snippet −
M2<-matrix(x2,ncol=2,byrow=TRUE) M2
The following matrix is created −
[,1] [,2] [1,] 0.66716447 -0.122225066 [2,] -0.07647741 0.028916676 [3,] -0.39709805 1.641409012 [4,] -0.24942074 -0.158497321 [5,] 0.02107895 0.003907016 [6,] -2.05324534 0.979486325 [7,] -0.71567237 -0.499532064 [8,] -0.28274355 -1.111749126 [9,] -0.24421395 -0.615584797 [10,] -1.40823602 0.664978538 [11,] -1.13424418 1.906882422 [12,] -1.50972716 0.587050358 [13,] -0.04610703 0.402558630 [14,] -0.85797812 -0.948390838 [15,] -0.11944543 -1.415887582 [16,] -0.76236171 -0.500234600 [17,] -1.40270152 0.031947267 [18,] -1.85293591 -0.383315786 [19,] -1.35704286 0.023015415 [20,] 1.06800735 NA
Example 3
Consider the vector given below −
x3<-sample(0:9,79,replace=TRUE) length(x3)<-prod(dim(matrix(x3,ncol=4)))
Warning message
In matrix(x3, ncol = 4) : data length [79] is not a sub-multiple or multiple of the number of rows [20]
To create matrix of x3 on the above created matrix, add the following code to the above snippet −
M3<-matrix(x3,ncol=4,byrow=TRUE) M3
The following matrix is created −
[,1] [,2] [,3] [,4] [1,] 1 0 2 4 [2,] 1 5 6 7 [3,] 6 9 0 3 [4,] 3 2 2 7 [5,] 9 5 2 2 [6,] 6 5 1 2 [7,] 8 1 3 1 [8,] 3 6 4 7 [9,] 0 1 2 1 [10,] 8 0 6 0 [11,] 1 8 6 1 [12,] 2 5 0 6 [13,] 0 3 1 5 [14,] 4 3 7 7 [15,] 9 7 4 7 [16,] 2 4 6 0 [17,] 9 8 4 3 [18,] 9 9 0 6 [19,] 6 3 0 4 [20,] 2 4 1 NA
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