{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "background": "white",
  "padding": 5,
  "width": 700,
  "height": 500,
  "encode": {"update": {"stroke": {"value": "transparent"}}},
  "data": [
    {
      "name": "source_0",
      "url": "data/londonBoroughs.json",
      "format": {"type": "topojson", "feature": "boroughs"}
    },
    {
      "name": "source_2",
      "url": "data/londonTubeLines.json",
      "format": {"type": "topojson", "feature": "line"}
    },
    {
      "name": "source_1",
      "url": "data/londonCentroids.json",
      "format": {"type": "json"},
      "transform": [
        {
          "type": "formula",
          "expr": "indexof (datum.name,' ') > 0  ? substring(datum.name,0,indexof(datum.name, ' ')) : datum.name",
          "as": "bLabel"
        },
        {
          "type": "geojson",
          "fields": ["cx", "cy"],
          "signal": "layer_1_geojson_0"
        },
        {
          "type": "geopoint",
          "projection": "projection",
          "fields": ["cx", "cy"],
          "as": ["layer_1_x", "layer_1_y"]
        }
      ]
    }
  ],
  "projections": [
    {
      "name": "projection",
      "size": {"signal": "[width, height]"},
      "fit": {
        "signal": "[data('source_0'), layer_1_geojson_0, data('source_2')]"
      }
    }
  ],
  "marks": [
    {
      "name": "layer_0_marks",
      "type": "shape",
      "style": ["geoshape"],
      "from": {"data": "source_0"},
      "encode": {
        "update": {
          "stroke": {"value": "white"},
          "strokeWidth": {"value": 2},
          "fill": {"value": "#eee"},
          "ariaRoleDescription": {"value": "geoshape"}
        }
      },
      "transform": [{"type": "geoshape", "projection": "projection"}]
    },
    {
      "name": "layer_1_marks",
      "type": "text",
      "style": ["text"],
      "from": {"data": "source_1"},
      "encode": {
        "update": {
          "fill": {"value": "black"},
          "opacity": {"value": 0.6},
          "description": {
            "signal": "\"cx: \" + (format(datum[\"cx\"], \"\")) + \"; cy: \" + (format(datum[\"cy\"], \"\")) + \"; bLabel: \" + (isValid(datum[\"bLabel\"]) ? datum[\"bLabel\"] : \"\"+datum[\"bLabel\"])"
          },
          "x": {"field": "layer_1_x"},
          "y": {"field": "layer_1_y"},
          "text": {
            "signal": "isValid(datum[\"bLabel\"]) ? datum[\"bLabel\"] : \"\"+datum[\"bLabel\"]"
          },
          "fontSize": {"value": 8},
          "align": {"value": "center"},
          "baseline": {"value": "middle"}
        }
      }
    },
    {
      "name": "layer_2_marks",
      "type": "shape",
      "style": ["geoshape"],
      "from": {"data": "source_2"},
      "encode": {
        "update": {
          "strokeWidth": {"value": 2},
          "fill": {"value": "transparent"},
          "stroke": {"scale": "color", "field": "id"},
          "ariaRoleDescription": {"value": "geoshape"},
          "description": {
            "signal": "\"id: \" + (isValid(datum[\"id\"]) ? datum[\"id\"] : \"\"+datum[\"id\"])"
          }
        }
      },
      "transform": [{"type": "geoshape", "projection": "projection"}]
    }
  ],
  "scales": [
    {
      "name": "color",
      "type": "ordinal",
      "domain": [
        "Bakerloo",
        "Central",
        "Circle",
        "District",
        "DLR",
        "Hammersmith & City",
        "Jubilee",
        "Metropolitan",
        "Northern",
        "Piccadilly",
        "Victoria",
        "Waterloo & City"
      ],
      "range": [
        "rgb(137,78,36)",
        "rgb(220,36,30)",
        "rgb(255,206,0)",
        "rgb(1,114,41)",
        "rgb(0,175,173)",
        "rgb(215,153,175)",
        "rgb(106,114,120)",
        "rgb(114,17,84)",
        "rgb(0,0,0)",
        "rgb(0,24,168)",
        "rgb(0,160,226)",
        "rgb(106,187,170)"
      ]
    }
  ],
  "legends": [
    {
      "offset": 0,
      "orient": "bottom-right",
      "stroke": "color",
      "symbolType": "circle",
      "encode": {"symbols": {"update": {"fill": {"value": "transparent"}}}}
    }
  ]
}