How to divide matrix rows in R by row median?

To divide matrix row values by row median in R, we can follow the below steps −

• First of all, create a matrix.
• Then, use apply function to divide the matrix row values by row median.

Create the matrix

Let's create a matrix as shown below −

 Live Demo

M<-matrix(rpois(75,10),ncol=3) M

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

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

Divide the matrix row values by row median

Using apply function to divide the row values of M by row median −

 Live Demo

M<-matrix(rpois(75,10),ncol=3) M_new<-t(apply(M,1, function(x) x/median(x))) M_new

Output

         [,1]       [,2]    [,3] [1,] 1.5714286 0.8571429 1.0000000 [2,] 1.0000000 1.7500000 0.7500000 [3,] 1.0909091 1.0000000 0.5454545 [4,] 1.0000000 1.0000000 1.2727273 [5,] 1.0000000 1.3333333 1.0000000 [6,] 1.0000000 0.8000000 1.4000000 [7,] 0.8750000 1.6250000 1.0000000 [8,] 1.1538462 0.9230769 1.0000000 [9,] 1.0000000 3.0000000 1.0000000 [10,] 1.0000000 0.8571429 1.1428571 [11,] 0.8181818 1.0000000 1.0000000 [12,] 0.7142857 1.0000000 1.8571429 [13,] 1.5000000 1.0000000 1.0000000 [14,] 1.0000000 1.2000000 0.6000000 [15,] 1.0000000 1.4000000 1.0000000 [16,] 1.0000000 1.0909091 0.4545455 [17,] 1.3636364 1.0000000 1.0000000 [18,] 1.1250000 1.0000000 1.0000000 [19,] 1.0000000 0.4285714 1.1428571 [20,] 1.0000000 1.5000000 1.0000000 [21,] 1.0000000 1.1111111 0.8888889 [22,] 0.9166667 1.0833333 1.0000000 [23,] 1.0000000 1.3076923 0.6153846 [24,] 1.0000000 0.9166667 1.3333333 [25,] 1.0000000 1.0000000 0.2727273