{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "background": "white",
  "padding": 5,
  "width": 650,
  "height": 400,
  "data": [
    {
      "name": "source_0",
      "url": "https://raw.githubusercontent.com/vega/vega-datasets/main/data/zipcodes.csv",
      "format": {"type": "csv"},
      "transform": [
        {
          "type": "formula",
          "expr": "substring(datum.zip_code,0,1)",
          "as": "leading digit"
        },
        {
          "type": "geojson",
          "fields": ["longitude", "latitude"],
          "signal": "geojson_0"
        },
        {
          "type": "geopoint",
          "projection": "projection",
          "fields": ["longitude", "latitude"],
          "as": ["x", "y"]
        }
      ]
    }
  ],
  "projections": [
    {
      "name": "projection",
      "size": {"signal": "[width, height]"},
      "fit": {"signal": "geojson_0"},
      "type": "albersUsa"
    }
  ],
  "marks": [
    {
      "name": "marks",
      "type": "symbol",
      "style": ["circle"],
      "from": {"data": "source_0"},
      "encode": {
        "update": {
          "opacity": {"value": 0.7},
          "size": {"value": 3},
          "fill": {"scale": "color", "field": "leading digit"},
          "tooltip": {
            "signal": "isValid(datum[\"zip_code\"]) ? datum[\"zip_code\"] : \"\"+datum[\"zip_code\"]"
          },
          "ariaRoleDescription": {"value": "circle"},
          "description": {
            "signal": "\"longitude: \" + (format(datum[\"longitude\"], \"\")) + \"; latitude: \" + (format(datum[\"latitude\"], \"\")) + \"; leading digit: \" + (isValid(datum[\"leading digit\"]) ? datum[\"leading digit\"] : \"\"+datum[\"leading digit\"]) + \"; zip_code: \" + (isValid(datum[\"zip_code\"]) ? datum[\"zip_code\"] : \"\"+datum[\"zip_code\"])"
          },
          "x": {"field": "x"},
          "y": {"field": "y"},
          "shape": {"value": "circle"}
        }
      }
    }
  ],
  "scales": [
    {
      "name": "color",
      "type": "ordinal",
      "domain": {"data": "source_0", "field": "leading digit", "sort": true},
      "range": "category"
    }
  ],
  "legends": [
    {
      "fill": "color",
      "symbolType": "circle",
      "title": "leading digit",
      "encode": {"symbols": {"update": {"opacity": {"value": 0.7}}}}
    }
  ]
}