Syntax error How to convert values in alternate rows to negative in matrix in R?

How to convert values in alternate rows to negative in matrix in R?

To convert values in alternate rows to negative R matrix, we can follow the below steps −

  • First of all, create a matrix.

  • Then, use vector multiplication with 1 and minus 1 to convert values in alternate rows to negative.

Example

Create the matrix

Let’s create a matrix as shown below −

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

Convert values in alternate rows to negative

Using vector multiplication with 1 and minus 1 to convert values in alternate rows of column 1 of matrix M to negative −

M<-matrix(rpois(30,10),ncol=1)
M[,1]<-M[,1]*c(1,-1)
M

Output

     [,1]
[1,]   16
[2,]  -12
[3,]    8
[4,]  -16
[5,]    6
[6,]  -11
[7,]    9
[8,]   -6
[9,]    8
[10,]  -9
[11,]  13
[12,]  -4
[13,]  12
[14,] -10
[15,]  10
[16,]  -9
[17,]  11
[18,] -11
[19,]  10
[20,]  -6
[21,]   8
[22,]  -6
[23,]   4
[24,] -10
[25,]   7
[26,] -10
[27,]  12
[28,] -10
[29,]   7
[30,] -11
Updated on: 2021-11-15T06:45:04+05:30

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