qpK2R {qpgraph} | R Documentation

## Partial correlation coefficients

### Description

Obtains partial correlation coefficients from a given concentration matrix.

### Usage

    qpK2R(K)

### Arguments

`K` | concentration matrix.

### Details

Partial correlation coefficients are obtained from a concentration matrix by scaling it by its diagonal and swapping the sign of the off-diagonal elements.

### Value

A matrix with partial correlation coefficients.

### Author(s)

R. Castelo and A. Roverato

### References

Castelo, R. and Roverato, A. A robust procedure for Gaussian graphical model search from microarray data with p larger than n. J. Mach. Learn. Res., 7:2621-2650, 2006.

### See Also

`qpI2K`

### Examples

    nVar <- 50 # number of variables
    maxCon <- 5  # maximum connectivity per variable

    I <- qpRndGraph(n.vtx=nVar, n.bd=maxCon)
    K <- qpI2K(I)

    R <- qpK2R(K)

    # true partial correlation coefficients of the present edges
    summary(abs(R[upper.tri(R) & I]))

    # true partial correlation coefficients of the missing edges
    summary(abs(R[upper.tri(R) & !I]))

[Package qpgraph version 1.0.0 Index]