Modifying the Width of a Symbol Mark in Vega

Question

I want to label the symbols in my Vega graph. Some of the labels are long, extending beyond the boundaries of my symbols. How do I extend the width of a symbol to handle long labels?

Update: Is there a way of increasing the width of a symbol mark?

This is a link to my code.

N.B: I tried using rect marks, whose widths are easier to modify. But the aesthetics of the rect mark do not work for my use case. My use case is a Force Transform force-directed graph.

Answer 1

Here is a working example using your Vega spec with Force transform and text box using reactive geometry as suggested by David.

View in Vega online editor

{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "description": "A node-link diagram with force-directed layout, depicting character co-occurrence in the novel Les Misérables.",
  "width": 500,
  "height": 200,
  "autosize": "pad",
  "signals": [
    {
      "name": "nodeRadius",
      "value": 50,
      "bind": {"input": "range", "min": 1, "max": 100, "step": 1}
    },
    {
      "name": "nodeCharge",
      "value": -100,
      "bind": {"input": "range", "min": -100, "max": 10, "step": 1}
    },
    {
      "name": "linkDistance",
      "value": 66,
      "bind": {"input": "range", "min": 5, "max": 100, "step": 1}
    },
    {
      "name": "textPadding", 
      "value": 5,
      "bind": {"input": "range", "min": 0, "max": 20, "step": 1}
      },
    {
      "name": "cornerRadius", 
      "value": 10,
      "bind": {"input": "range", "min": 0, "max": 20, "step": 1}
    },
    { "name": "showSymbol", "value": false, "bind": {"input": "checkbox"} },

  ],
  "data": [
    {
      "name": "node_data",
      "values": [
        {"name": "A Name", "type": "node", "1d": 0},
        {"name": "A Very Long Name", "type": "node", "1d": 1}
      ]
    },
    {"name": "edge_data", "values": [{"source": 0, "target": 1}]}
  ],
  "marks": [
   {
      "type": "symbol",
      "name": "nodes",
      "from": {"data": "node_data"},
      "encode": {
        "update": {
          "fill": {"value": "grey"},
          "opacity": {"signal": "showSymbol ? 0.5 : 0"},
          "size": {"signal": "PI * nodeRadius * nodeRadius"},
          "shape": {"value": "circle"}
        }
      },
      "transform": [
        {
          "type": "force",
          "iterations": 300,
          "static": {"signal": "false"},
          "signal": "force",
          "forces": [
            {
              "force": "center",
              "x": {"signal": "width/2"},
              "y": {"signal": "height/2"}
            },
            {"force": "collide", "radius": {"signal": "nodeRadius"}},
            {"force": "nbody", "strength": {"signal": "nodeCharge * 10"}},
            {
              "force": "link",
              "links": "edge_data",
              "distance": {"signal": "linkDistance"}
            }
          ]
        }
      ]
    },
    {
      "type": "path",
      "from": {"data": "edge_data"},
      "interactive": false,
      "encode": {
        "update": {"stroke": {"value": "#ccc"}, "strokeWidth": {"value": 0.5}}
      },
      "transform": [
        {
          "type": "linkpath",
          "require": {"signal": "force"},
          "shape": "line",
          "sourceX": "datum.source.x",
          "sourceY": "datum.source.y",
          "targetX": "datum.target.x",
          "targetY": "datum.target.y"
        }
      ]
    },
    {
      "type": "text",
      "name": "textmark",
      "from": {"data": "nodes"},
      "interactive": false,
      
      "encode": {
        "enter": {"fill": {"value": "black"}, "fontSize": {"value": 16}},
        "update": {
          "y": {"field": "y", "offset": {"signal": "nodeRadius * -0.1"}},
          "x": {"field": "x"},
          "text": {"field": "datum.name"},
          "align": {"value": "center"},
          "baseline": {"value": "middle"}
        }
      },
       "zindex": 1
    },
    {
      "name": "rectmark",
      "type": "rect",
      "from": {"data": "textmark"},
      "encode": {
        "update": {
          "x": {"field": "bounds.x1", "round": true,  "offset": {"signal": "-textPadding"}},
          "x2": {"field": "bounds.x2", "round": true, "offset": {"signal": "textPadding"}},
          "y": {"field": "bounds.y1", "round": true, "offset": {"signal": "-textPadding"}},
          "y2": {"field": "bounds.y2", "round": true, "offset": {"signal": "textPadding"}},
          "cornerRadius": {"signal": "cornerRadius"},
          "fill": {"value": "aliceblue"},
          "stroke": {"value": "steelblue"}
        }
      }
    }
  ]
}