Creates a Symmetric Matrix from a Vector

Takes a vector and, if the vector is of the correct lenght to be made into a symmetric matrix, performs the conversion.

vec2symmat(invec, diag = 1, byrow = TRUE)

Arguments

invec	The input vector
diag	The value for the diagonal
byrow	Logical. Whether the upper-triangle should be filled in by row

Value

A matrix

References

http://stackoverflow.com/a/18598933/1270695

Author

Ananda Mahto

Examples

myvec <- c(-.55, -.48, .66, .47, -.38, -.46)
vec2symmat(myvec)
#>       [,1]  [,2]  [,3]  [,4]
#> [1,]  1.00 -0.55 -0.48  0.66
#> [2,] -0.55  1.00  0.47 -0.38
#> [3,] -0.48  0.47  1.00 -0.46
#> [4,]  0.66 -0.38 -0.46  1.00

vec2symmat(1:15, diag = 0)
#>      [,1] [,2] [,3] [,4] [,5] [,6]
#> [1,]    0    1    2    3    4    5
#> [2,]    1    0    6    7    8    9
#> [3,]    2    6    0   10   11   12
#> [4,]    3    7   10    0   13   14
#> [5,]    4    8   11   13    0   15
#> [6,]    5    9   12   14   15    0
vec2symmat(1:15, diag = 0, byrow = FALSE)
#>      [,1] [,2] [,3] [,4] [,5] [,6]
#> [1,]    0    1    2    4    7   11
#> [2,]    1    0    3    5    8   12
#> [3,]    2    3    0    6    9   13
#> [4,]    4    5    6    0   10   14
#> [5,]    7    8    9   10    0   15
#> [6,]   11   12   13   14   15    0