R: Extract Diagonal of a Matrix

diag2vec {OpenMx} | R Documentation

## Extract Diagonal of a Matrix

### Description

Given an input matrix, `diag2vec` returns a column vector of the elements along the diagonal.

### Usage

    diag2vec(x)

### Arguments

`x` | an input matrix.

### Details

Similar to the function `diag`, except that the input argument is always treated as a matrix (i.e., it doesn't have diag()'s functions of returning an Identity matrix from an nrow specification, nor to return a matrix wrapped around a diagonal if provided with a vector). To get vector2matrix functionality, call `vec2diag`.

### See Also

`vec2diag`

### Examples

    diag2vec(matrix(1:9, nrow=3))
    #      [,1]
    # [1,]    1
    # [2,]    5
    # [3,]    9

    diag2vec(matrix(1:12, nrow=3, ncol=4))
    #      [,1]
    # [1,]    1
    # [2,]    5
    # [3,]    9

[Package OpenMx version 2.11.4 Index]