| c  layout data nodes edges |
c := RSCanvas new.
data := NeoJSONReader fromString: (ZnEasy get: 'https://cytoscape.org/cytoscape.js-euler/example-graphs/planar-chain.json') contents.

nodes := data select: [ :obj | (obj at: #group) =#nodes ].
edges := data select: [ :obj | (obj at: #group) =#edges ].
edges := edges collect: [ :ed | | d |
	d := ed at: #data.
	(d at: #source) -> (d at: #target) ].

c addAll: (nodes collect: [ :obj | | pos d |
	pos := obj at: #position.
	d := obj at: #data.
	pos := (pos at: #x) @ (pos at: #y).
	RSEllipse new
		draggable;
		model: (d at: #id);
		color: Color green darker;
		popup;
		position: pos;
		size: 10;
		yourself.
	 ]).

RSEdgeBuilder line
	canvas: c;
	shapes: c nodes;
	color: (Color purple alpha: 0.2);
	useAssociations: edges.
"layout := RSForceBasedLayout new 
	initialLayout: RSNoLayout new;
	nodes: c nodes;
	edges: c edges;
	start;
	yourself.
c newAnimation repeat onStepDo: [ :t | 
	layout step. 
	c zoomToFit ]."
RSForceBasedLayout on: c nodes.
c zoomToFit.
c