# How to subset a matrix in R by ignoring a value in one of the columns?

To subset a matrix in R by ignoring a value in one of the columns, we can follow the below steps −

• First of all, create a matrix.

• Then, use single square brackets to subset the matrix by ignoring a value in one of the columns.

## Example

#### Create the matrix

Let’s create a matrix as shown below −

M<-matrix(rpois(100,5),ncol=4)
M

## Output

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

    [,1] [,2] [,3] [,4]
[1,]  7   8    6    6
[2,]  4   5    2    7
[3,]  6   4    7    4
[4,]  3   8    6    2
[5,]  5   8    4    7
[6,]  4   7    3    2
[7,]  7   4    7    6
[8,]  1   8    7    5
[9,]  3   4    3    3
[10,] 5   3    3    2
[11,] 1   6    7    6
[12,] 9   2    4    0
[13,] 4   4    1    6
[14,] 8   9    5    6
[15,] 6   5    8    1
[16,] 5   6    5    6
[17,] 2   4    5    5
[18,] 4   8    6    7
[19,] 4  11    8    4
[20,] 4   4   10    9
[21,] 5   6    6    4
[22,] 4   2    6    5
[23,] 6   8    6    6
[24,] 5   6    3    3
[25,] 6   6    6    3

Subset the matrix by ignoring a value in one of the columns

Using single square brackets to subset the matrix M by ignoring 4 in column 1 as shown below −

M<-matrix(rpois(100,5),ncol=4)
M[M[,1]!=4,]

## Output

   [,1] [,2] [,3] [,4]
[1,]  7   8   6    6
[2,]  6   4   7    4
[3,]  3   8   6    2
[4,]  5   8   4    7
[5,]  7   4   7    6
[6,]  1   8   7    5
[7,]  3   4   3    3
[8,]  5   3   3    2
[9,]  1   6   7    6
[10,] 9   2   4    0
[11,] 8   9   5    6
[12,] 6   5   8    1
[13,] 5   6   5    6
[14,] 2   4   5    5
[15,] 5   6   6    4
[16,] 6   8   6    6
[17,] 5   6   3    3
[18,] 6   6   6    3