[R] path.diagram in SEM--display covariances without variances

[Dustin Fife]

Forgive me if I'm posting to the wrong place....It's my first time posting.

Here's the situation: I'm using the sem package and making path
diagrams using path.diagrams. Suppose I have the following code:

#install.packages("ggm")
require(ggm)
cor = rcorr(7)
nm = c("SOF", "IWF", "PWF", "FSC", "FSF", "EF", "GPA")


ram = specify.model()
	PWF -> FSF, a, NA
	PWF -> FSC, b, NA
	SOF -> FSF, c, NA
	SOF -> FSC, d, NA
	IWF -> FSF, e, NA
	IWF -> FSC, f, NA		
	FSC -> EF, g, NA
	FSF -> EF, h, NA
	EF -> GPA, i, NA
	PWF <-> IWF, j, NA
	PWF <-> SOF, k, NA
	SOF <-> IWF, l, NA
	PWF <-> PWF, d1, NA
	SOF <-> SOF, d2, NA
	IWF <-> IWF, d3, NA
	FSC <-> FSC, d4, NA
	FSF <-> FSF, d5, NA
	EF <-> EF, d6, NA
	GPA <-> GPA, d7, NA			
				


sem.mod = sem(ram, cor, N=1656, obs.variables=nm)

path.diagram(sem.mod, 'path/to/file/plot', ignore.double=FALSE,
edge.labels="values", standardize=TRUE, min.rank=c("IWF", "SOF",
"PWF"))

The diagram is produces is hard to read because of the many variances
that are shown. The covariance estimates are important for my diagram,
but the variances are not. Is there a way to suppress the variance
arrows without suppressing the covariance arrows?

-- 
Dustin Fife
Graduate Student, Quantitative Psychology
University of Oklahoma