onyxR

An R package for calling Onyx GUI from R when using OpenMx or lavaan packages for Structural Equation Modelling. The package provides a simple onyx() function that takes either an OpenMx model or a lavaan model (either a fitted lavaan model or string specification). If a local onyx executable is available, its path can be passed to the function. Otherwise, it will attempt to download a copy of Onyx from the official repository. A recent version of JAVA (version 1.6+) is required to be installed on the system.

Install

To install the onyxR package directly from GitHub, copy the following line into R:

source('https://raw.githubusercontent.com/brandmaier/onyxR/master/tools/install.R')

Usage

Using onyxR is as simple as that. In lavaan

HS.model <- ' visual  =~ x1 + x2 + x3 
              textual =~ x4 + x5 + x6
              speed   =~ x7 + x8 + x9 '

fit <- cfa(HS.model, data = HolzingerSwineford1939)

summary(fit, fit.measures = TRUE)

onyx(fit)

Alternatively, we can use onyxR to generate a path diagram for an OpenMx RAM-type model:

data(demoOneFactor)
manifests <- names(demoOneFactor)
latents <- c("G")
factorModel <- mxModel("One Factor",
                       type="RAM",
                       manifestVars = manifests,
                       latentVars = latents,
                       mxPath(from=latents, to=manifests),
                       mxPath(from=manifests, arrows=2),
                       mxPath(from=latents, arrows=2,
                              free=FALSE, values=1.0),
                       mxData(cov(demoOneFactor), type="cov",
                              numObs=500))
fit <- mxRun(factorModel)

onyx(fit)

Demo

In a simple demo, we have wrapped the above example. We define the HS model with three independent factors in lavaan and pass this to Onyx to display the path diagram.

require(onyxR)
demo(lavaanHS)
```