omxGraphviz help (making path diagrams)

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OpenMx can output path diagrams using the dot syntax. You can learn about this language for describing path diagrams at several online tutorials: An Introduction to GraphViz and dot - O'Reilly Media, Using GraphViz, a Brief Tutorial | Orient Lodge. The R for generating a path diagram from a model is straightforward:

	 omxGraphviz(model, dotFilename="")

(currently for RAM models only) If you leave parameter 2 blank, the dot file will be output into the R console. Here is a complete example:

require(OpenMx)
data(demoOneFactor)
manifests <- names(demoOneFactor)
latents <- c("G1")
model1 <- 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=F, values=1.0),
	mxData(cov(demoOneFactor), type="cov",numObs=500)
)
omxGraphviz(model1, "one-factor-generated.dot")

Rendering the output

dot output is in simple text file describing the latent and manifest variables (nodes) and their connections (edges) of a diagram. To visualize the diagram, this .dot script must be processed by an application such as Graphviz. This app does a nice job of rendering .dot. Other programmes that can open .dot include Omnigraffle. This site https://ashitani.jp/gv/ has an online renderer, which is handy for cut and paste: Paste this in to see a sex lim model: t1 [label="Pt1", shape=box] t2 [label="Pt2", shape=box] Af -> Am [dir=both, label="ag"] Cf -> Cm [dir=both, label="eta"] Af -> t1 [label="af"] Cf -> t1 [label="cf"] Ef -> t1 [label="ef"] Am -> t2 [label="am"] Cm -> t2 [label="cm"] Em -> t2 [label="em"] {rank=min; Af; Cf; Ef; Am; Cm; Em; }; {rank=max; t1; t2};