lowerTri2matrix: Reconstruct a symmetric matrix from a distance... In WGCNA: Weighted Correlation Network Analysis

Description

Assuming the input vector contains a vectorized form of the distance representation of a symmetric matrix, this function creates the corresponding matrix. This is useful when re-forming symmetric matrices that have been vectorized to save storage space.

Usage

 `1` ```lowerTri2matrix(x, diag = 1) ```

Arguments

 `x` a numeric vector `diag` value to be put on the diagonal. Recycled if necessary.

Details

The function assumes that `x` contains the vectorized form of the distance representation of a symmetric matrix. In particular, `x` must have a length that can be expressed as n*(n-1)/2, with n an integer. The result of the function is then an n times n matrix.

Value

A symmetric matrix whose lower triangle is given by `x`.

Peter Langfelder

Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20``` ``` # Create a symmetric matrix m = matrix(c(1:16), 4,4) mat = (m + t(m)); diag(mat) = 0; # Print the matrix mat # Take the lower triangle and vectorize it (in two ways) x1 = mat[lower.tri(mat)] x2 = as.vector(as.dist(mat)) all.equal(x1, x2) # The vectors are equal # Turn the vectors back into matrices new.mat = lowerTri2matrix(x1, diag = 0); # Did we get back the same matrix? all.equal(mat, new.mat) ```

WGCNA documentation built on March 1, 2021, 1:05 a.m.