rmatrixsymmetric

How do I make a symmetric matrix using R?

I am trying to make a symmetric matrix using R. I already have a matrix. My matrix is very big so below is a simple example.

EX.

1 2 3

4 5 6

7 8 9

I need to make them like this.

1 2+4 3+7

4+2 5 6+8

7+3 8+6 9

//So I tried this. // mat is the matrix I am using.

lowervector <- square_07[lower.tri(square_07, diag = FALSE)]

uppervector <- square_07[upper.tri(square_07, diag = FALSE)]

lowermat <- square_07 uppermat <- square_07

lowermat[lower.tri(lowermat, diag = FALSE)] <- t(square_07)[lower.tri(square_07, diag = FALSE)]

uppermat[upper.tri(uppermat, diag = FALSE)] <- t(square_07)[upper.tri(square_07, diag = FALSE)]

When I execute the last 2 lines, an error occurs;

Subscript 'upper.tri(uppermat, diag = FALSE)' is a matrix, the data 't[upper.tri(square_07, diag = FALSE)]' must have size 1.

You should know. The upper matrix is just an example. My actual matrix is much more bigger. It is a 248*248 matrix.

How can I solve this problem?

Solution

  • You can try this -

    mat[upper.tri(mat)] <- mat[upper.tri(mat)] + mat[lower.tri(mat)]
mat[lower.tri(mat)] <- mat[upper.tri(mat)]
mat

#     [,1] [,2] [,3]
#[1,]    1    6   10
#[2,]    6    5   14
#[3,]   10   14    9

    data

    mat <- structure(c(1L, 4L, 7L, 2L, 5L, 8L, 3L, 6L, 9L), .Dim = c(3L, 3L))
mat

#     [,1] [,2] [,3]
#[1,]    1    2    3
#[2,]    4    5    6
#[3,]    7    8    9