Syntax error How to divide data.table object rows by row median in R?

How to divide data.table object rows by row median in R?

To divide the row values by row median in R’s data.table object, we can follow the below steps −

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

Create the data.table object

Let's create a data frame as shown below −

> library(data.table)
> x<-rpois(25,5)
> y<-rpois(25,2)
> z<-rpois(25,10)
> DT<-data.table(x,y,z)
> DT

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

    x y  z
1:  5 3  2
2:  1 3  7
3:  6 0 13
4:  6 2 10
5:  8 1  9
6:  9 1 10
7:  4 1 10
8:  7 2 12
9:  3 5  8
10: 5 2  7
11: 9 3 11
12: 3 2  8
13: 3 1 10
14: 3 2 10
15: 2 2 14
16: 6 2 10
17: 3 4  6
18: 4 2 11
19: 6 0  8
20: 5 3  9
21: 4 2  4
22: 4 3 12
23: 2 2  6
24: 7 1 15
25: 5 1 10
    x y z

Divide the data.table object row values by row median

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

> library(data.table)
> x<-rpois(25,5)
> y<-rpois(25,2)
> z<-rpois(25,10)
> DT<-data.table(x,y,z)
> DT_new<-t(apply(DT,1, function(x) x/median(x)))
> DT_new

Output

x y z
[1,] 1.6666667 1.0000000 0.6666667
[2,] 0.3333333 1.0000000 2.3333333
[3,] 1.0000000 0.0000000 2.1666667
[4,] 1.0000000 0.3333333 1.6666667
[5,] 1.0000000 0.1250000 1.1250000
[6,] 1.0000000 0.1111111 1.1111111
[7,] 1.0000000 0.2500000 2.5000000
[8,] 1.0000000 0.2857143 1.7142857
[9,] 0.6000000 1.0000000 1.6000000
[10,] 1.0000000 0.4000000 1.4000000
[11,] 1.0000000 0.3333333 1.2222222
[12,] 1.0000000 0.6666667 2.6666667
[13,] 1.0000000 0.3333333 3.3333333
[14,] 1.0000000 0.6666667 3.3333333
[15,] 1.0000000 1.0000000 7.0000000
[16,] 1.0000000 0.3333333 1.6666667
[17,] 0.7500000 1.0000000 1.5000000
[18,] 1.0000000 0.5000000 2.7500000
[19,] 1.0000000 0.0000000 1.3333333
[20,] 1.0000000 0.6000000 1.8000000
[21,] 1.0000000 0.5000000 1.0000000
[22,] 1.0000000 0.7500000 3.0000000
[23,] 1.0000000 1.0000000 3.0000000
[24,] 1.0000000 0.1428571 2.1428571
[25,] 1.0000000 0.2000000 2.0000000
Updated on: 2021-08-13T10:16:59+05:30

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