How to convert values greater than a threshold into 1 in column of a matrix in R?

To convert values greater than a threshold into 1 in matrix in R data frame, we can follow the below steps −

  • First of all, create a matrix.

  • Then, use ifelse function to convert values greater than a threshold into 1.

Example

Create the matrix

Let’s create a matrix as shown below −

M<-matrix(rnorm(50),ncol=2)
M

Output

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

        [,1]         [,2]
[1,]   1.35131510  1.37522054
[2,]  -1.13345162  0.36286206
[3,]   0.63015182 -0.03290929
[4,]   0.92621651  1.31680036
[5,]  -0.82421679  0.32648195
[6,]   0.97343371 -1.07267437
[7,]   1.64987699 -0.78395936
[8,]  -1.26893096 -0.86729417
[9,]   1.43618275 -0.35711054
[10,]  0.47313589  1.33716595
[11,] -0.62682302 -0.11872530
[12,] -1.55459406  0.60669510
[13,]  0.71674609  0.38263617
[14,]  0.15818009  0.40835948
[15,] -0.63320156 -0.06941598
[16,] -0.18245803 -0.69972541
[17,] -0.83207399 -2.18994824
[18,] -0.50880490 -1.11029099
[19,]  0.09978232  0.84119858
[20,] -0.53728939 -0.42712942
[21,]  0.78737850  0.64063631
[22,] -0.54197740  1.52800265
[23,]  0.64130714  0.03383875
[24,]  0.54300424 -0.48200610
[25,] -0.91642041 -0.27952213

Convert values greater than a threshold to 1

Using ifelse function to convert values greater than a threshold into 1 in column 1 of matrix M −

M<-matrix(rnorm(50),ncol=2)
M[,1]<-ifelse(M[,1]>0.5,1,M[,1])
M

Output

        [,1]         [,2]
[1,]   1.00000000  1.37522054
[2,]  -1.13345162  0.36286206
[3,]   1.00000000 -0.03290929
[4,]   1.00000000  1.31680036
[5,]  -0.82421679  0.32648195
[6,]   1.00000000 -1.07267437
[7,]   1.00000000 -0.78395936
[8,]  -1.26893096 -0.86729417
[9,]   1.00000000 -0.35711054
[10,]  0.47313589  1.33716595
[11,] -0.62682302 -0.11872530
[12,] -1.55459406  0.60669510
[13,]  1.00000000  0.38263617
[14,]  0.15818009  0.40835948
[15,] -0.63320156 -0.06941598
[16,] -0.18245803 -0.69972541
[17,] -0.83207399 -2.18994824
[18,] -0.50880490 -1.11029099
[19,]  0.09978232  0.84119858
[20,] -0.53728939 -0.42712942
[21,]  1.00000000  0.64063631
[22,] -0.54197740  1.52800265
[23,]  1.00000000  0.03383875
[24,]  1.00000000 -0.48200610
[25,] -0.91642041 -0.27952213

Updated on: 11-Nov-2021

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