{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "width": 450,
  "height": 280,
  "autosize": "none",

  "signals": [
    {
      "name": "selected", "value": null,
      "on": [
        {"events": "symbol:mouseover", "update": "datum"},
        {"events": "symbol:mouseout", "update": "null"}
      ]
    }
  ],

  "projections": [
    {
      "name": "projection",
      "type": "albersUsa",
      "scale": 600,
      "translate": [{"signal": "width / 2"}, {"signal": "height / 2"}]
    }
  ],

  "data": [
    {
      "name": "states",
      "url": "data/us-10m.json",
      "format": {"type": "topojson", "feature": "states"},
      "transform": [
        {
          "type": "geopath",
          "projection": "projection"
        }
      ]
    },
    {
      "name": "capitals",
      "url": "data/us-state-capitals.json",
      "transform": [
        {
          "type": "geopoint",
          "projection": "projection",
          "fields": ["lon", "lat"]
        }
      ]
    },
    {
      "name": "selected",
      "source": "capitals",
      "transform": [
        {
          "type": "filter",
          "expr": "datum === selected"
        }
      ]
    }
  ],

  "marks": [
    {
      "type": "path",
      "from": {"data": "states"},
      "encode": {
        "enter": {
          "strokeWidth": {"value": "1"},
          "stroke": {"value": "#fff"},
          "fill": {"value": "#ddd"},
          "path": {"field": "path"}
        }
      }
    },
    {
      "type": "symbol",
      "interactive": false,
      "from": {"data": "capitals"},
      "encode": {
        "enter": {
          "shape": {"value": "M0,.5L.6,.8L.5,.1L1,-.3L.3,-.4L0,-1L-.3,-.4L-1,-.3L-.5,.1L-.6,.8L0,.5Z"},
          "fill": {"value": "#639"}
        },
        "update": {
          "x": {"field": "x"},
          "y": {"field": "y"}
        }
      }
    },
    {
      "type": "symbol",
      "from": {"data": "capitals"},
      "encode": {
        "enter": {
          "shape": "circle",
          "size": {"value": 200},
          "fill": {"value": "transparent"}
        },
        "update": {
          "x": {"field": "x"},
          "y": {"field": "y"}
        }
      }
    },
    {
      "type": "text",
      "interactive": false,
      "from": {"data": "selected"},
      "encode": {
        "enter": {
          "fill": {"value": "#639"},
          "fontSize": {"value": 9},
          "align": {"value": "center"},
          "baseline": {"value": "bottom"},
          "text": {"field": "city"}
        },
        "update": {
          "x": {"field": "x"},
          "y": {"field": "y", "offset": -5}
        }
      }
    }
  ]
}
