{
    "basis": {
        "type": "graph"
    },
    "data": {
        "type": "json",
        "values": {
            "persons": [
                {
                    "id": "node1",
                    "label": "node1",
                    "cost": 60,
                    "type": "A"
                },
                {
                    "id": "node2",
                    "label": "node2",
                    "cost": 25,
                    "type": "B"
                },
                {
                    "id": "node3",
                    "label": "node3",
                    "cost": 25,
                    "type": "B"
                }
            ],
            "relation": [
                {
                    "source": "node1",
                    "target": "node2",
                    "weight": 5,
                    "type": "X"
                },
                {
                    "source": "node2",
                    "target": "node3",
                    "weight": 10,
                    "type": "Y"
                }
            ]
        }
    },
    "layout": {
        "type": "force",
        "nodes": "persons",
        "links": "relation"
    },
    "layer": [
        {
            "nodes": {
                "mark": "point",
                "encoding": {
                    "size": {
                        "field": "cost",
                        "type": "quantitative"
                    },
                    "color": {
                        "field": "type",
                        "type": "nominal"
                    }
                }
            },
            "links": {
                "mark": "line",
                "encoding": {
                    "size": {
                        "field": "weight",
                        "type": "quantitative"
                    }
                }
            }
        }
    ]
}