Copyright © 2007-2016 The OpenMx Project

Published on *OpenMx* (http://openmx.ssri.psu.edu)

Wiki home page [1]

Ideas and example functions that extend OpenMx, encapsulate tedious work, and make scripts easier to write or more compact.

You will probably define helper functions, especially for summarising the output of model you use frequently.

There are libraries of helpers that work with OpenMx including

- https://github.com/tbates/umx
- install.packages("semTools")

Some how-to helpers are listed here:

source [2]

readLowerTriangle row) next X[row,col]An alternative using matrix indexing would be:

read.lower.triangleSee also read.moments() in http://cran.r-project.org/web/packages/sem/sem.pdf

require(sem) # install.packages("sem", dep=T)

read.moments(file = "", diag = TRUE,

names = as.character(paste("X", 1:n, sep = "")))## Converting a correlation matrix to a covariance matrix

If you are reanalysing published data, you may only have a correlation matrix and the SD for each variable. You can upconvert this to a covariance matrix with cor2cov(matrix, sd) from the MBESS package

http://rss.acs.unt.edu/Rdoc/library/MBESS/html/cor2cov.html

**Links**

[1] http://openmx.psyc.virginia.edu/wiki/main-page

[2] http://openmx.ssri.psu.edu/thread/198