Syntax error How to change the sign of even number rows in single column matrix in R?

How to change the sign of even number rows in single column matrix in R?

To change the sign of even number rows in R matrix, we can follow the below steps −

  • First of all, create a matrix.

  • Then, use vector multiplication with 1 and minus 1 to change the sign of even number rows.

Example

Create the matrix

Let’s create a matrix as shown below −

M<-matrix(rpois(30,5),ncol=1)
M

Output

On executing, the above script generates the below output(this output will vary on your system due to randomization) −

     [,1]
[1,]   4
[2,]   5
[3,]  10
[4,]   6
[5,]   4
[6,]   4
[7,]   4
[8,]   4
[9,]   1
[10,]  6
[11,]  2
[12,]  4
[13,]  5
[14,]  5
[15,]  2
[16,]  6
[17,]  4
[18,]  7
[19,]  2
[20,] 10
[21,]  3
[22,]  5
[23,]  9
[24,]  4
[25,]  4
[26,]  4
[27,]  5
[28,]  6
[29,]  5
[30,]  6

Change the sign of even number rows

Using vector multiplication with 1 and minus 1 to change the sign of even number rows in column 1 of matrix M −

M<-matrix(rpois(30,5),ncol=1)
M[,1]<-M[,1]*c(1,-1)
M

Output

    [,1]
[1,]   4
[2,]  -5
[3,]  10
[4,]  -6
[5,]   4
[6,]  -4
[7,]   4
[8,]  -4
[9,]   1
[10,] -6
[11,]  2
[12,] -4
[13,]  5
[14,] -5
[15,]  2
[16,] -6
[17,]  4
[18,] -7
[19,]  2
[20,] -10
[21,]  3
[22,] -5
[23,]  9
[24,] -4
[25,]  4
[26,] -4
[27,]  5
[28,] -6
[29,]  5
[30,] -6
Updated on: 2021-11-10T07:06:54+05:30

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