How to Extract Diagonal Elements of a Matrix in R Without Using diag Function?

In this article, we will see how to extract diagonal elements of a matrix in R Programming Language without using diag() function.

Matrix is a rectangular arrangement of numbers in rows and columns. In a matrix, as we know rows are the ones that run horizontally and columns are the ones that run vertically. In R programming, matrices are two-dimensional, homogeneous data structures.

matrix[row(matrix)==col(matrix)]

where, matrix is the input matrix. row() will check row elements and col() will check column elements.

Example 1:

In this example, we will create 5*5 matrix and display the diagonal elements.

Output:

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

Example 2:

In this example, we will create 3*3 matrix and display the diagonal elements.

Output:

 [,1] [,2] [,3]
[1,] 1 5 9
[2,] 3 6 6
[3,] 4 7 3
[1] 1 6 3