Using DiagrammeR for Path Diagrams (SEM)

Question

I´m testing the capabilities of the new DiagrammeR-package for visualisation of structural equation models.

My goal is, to get a plot like this:

Perhaps I need to find a ressource on how to specify the orientation of edges and nodes, because - with DiagrammeR - I can only do a plot like this right now:

devtools::install_github('rich-iannone/DiagrammeR')
library('DiagrammeR')

#----------

test<-grViz("     
digraph CFA{

# latent variables
node [shape=circle]
latent_a [group='a']; 
latent_b [group='b'];

#regressions
latent_a -> latent_b [label='0.279'];

#measurement model for latent a
subgraph A{
node [shape=box]
ind_1; 
ind_2; 
ind_3; 
latent_a -> ind_1 [label='0.636'];
latent_a -> ind_2 [label='0.825'];
latent_a -> ind_3 [label='0.829'];
}

#measurement model for latent b
subgraph B{
node [shape=box]
ind_4 ; 
ind_5 ;
latent_b -> ind_4 [label='1.027'];
latent_b -> ind_5 [label='0.626'];
}

#residuals
node [shape=circle]
e1 ; 
e4 ;
e5 ;
e6 ;
e1 -> ind_1;
e4 -> ind_4;
e5 -> ind_5;
e6 -> latent_b;

#residual covariances
ind_1 -> ind_2 [dir=both];
}      
")
test

I would be thankful for any hints.

PS: Perhaps my DiagrammeR-Code looks funny. I´ve tried to write it the same way, a model is specified in lavaan. Perhaps there will be a way to translate between both packages in the future. I think, this could be possible.

Answer 1

I came up with something that is a bit manual but I'm sure it's possible to generate the DOT code by making an appropriate R function. Here is the manual solution:

devtools::install_github("rich-iannone/DiagrammeR")
library(DiagrammeR)

grViz("
digraph SEM {

graph [layout = neato,
       overlap = true,
       outputorder = edgesfirst]

node [shape = rectangle]

a [pos = '-4,1!', label = 'e1', shape = circle]
b [pos = '-3,1!', label = 'ind_1']
c [pos = '-3,0!', label = 'ind_2']
d [pos = '-3,-1!', label = 'ind_3']
e [pos = '-1,0!', label = 'latent a', shape = ellipse]
f [pos = '1,0!', label = 'latent b', shape = ellipse]
g [pos = '1,1!', label = 'e6', shape = circle]
h [pos = '3,1!', label = 'ind_4']
i [pos = '3,-1!', label = 'ind_5']
j [pos = '4,1!', label = 'e4', shape = circle]
k [pos = '4,-1!', label = 'e5', shape = circle]

a->b
e->b [label = '0.6']
e->c [label = '0.6']
e->d [label = '0.6']

e->f [label = '0.321', headport = 'w']
g->f [tailport = 's', headport = 'n']

d->c [dir = both]

f->h [label = '0.6', tailport = 'ne', headport = 'w']
f->i [label = '0.6']

j->h
k->i

}
")