Building on top of the code presented in the Getting Started with the MMT API guide:
// Your config
val mainTheory = ctrl.get(DPath(URI("http://cds.omdoc.org/urtheories")) ? "NatArith")
val svgFilePath = (ctrl.getHome / "out.svg").getAbsolutePath
val tgExporter = new TheoryGraphExporter
tgExporter.init(ctrl)
val graph = tgExporter.buildGraph(mainTheory)
val svgContents = new DotToSVG(File("dot")).apply(graph)
val writer = new OutputStreamWriter(new FileOutputStream(svgFilePath), Charset.forName("UTF-8").newEncoder())
writer.write(svgContents)
writer.close()
This needs the command dot from the software GraphViz to be installed and available on your environment PATH. Alternatively, you can just print out the string graph and then render your file online on http://www.webgraphviz.com/.