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Make a matrix symmetric by mirroring one triangle

Source: R/FUNCTIONS_MATRIX.R
symmetric_matrix.Rd

Copies the lower or upper triangle of a square matrix onto the opposite triangle, producing a symmetric matrix; optionally replaces the diagonal. The row names are set to the column names, so both sides carry the same labels.

Usage

symmetric_matrix(matrix, duplicate = "lower", diagonal = NULL)

Arguments

matrix

A square matrix. Unlike matrix_triangle, a data frame is not accepted; convert it with as.matrix() first.

duplicate

Character. Use "lower" (default) to copy the lower triangle into the upper, or "upper" to copy the upper triangle into the lower.

diagonal

Value(s) to place on the diagonal: a single value (e.g. NA) or one value per diagonal element. Leave it out to keep the original diagonal; passing NULL explicitly is an error.

Value

A symmetric matrix with the same dimensions as matrix, whose row names are the column names of matrix.

See also

matrix_triangle, display_upper_lower_triangle

Examples

m_lower<-matrix_triangle(matrix(1:9,nrow=3,ncol=3),type="lower",diagonal=NA)
m_upper<-matrix_triangle(matrix(11:19,nrow=3,ncol=3),type="upper",diagonal=NA)
symmetric_matrix(matrix=m_lower,duplicate="lower",diagonal=NA)
#>      [,1] [,2] [,3]
#> [1,]   NA    2    3
#> [2,]    2   NA    6
#> [3,]    3    6   NA
symmetric_matrix(matrix=m_upper,duplicate="upper",diagonal=NA)
#>      [,1] [,2] [,3]
#> [1,]   NA   14   17
#> [2,]   14   NA   18
#> [3,]   17   18   NA