{
    "height": 500,
    "config": {
        "view": {
            "stroke": null
        }
    },
    "width": 800,
    "$schema": "https://vega.github.io/schema/vega-lite/v3.json",
    "projection": {
        "type": "albersUsa"
    },
    "layer": [
        {
            "mark": "geoshape",
            "data": {
                "url": "https://vega.github.io/vega-lite/data/us-10m.json",
                "format": {
                    "feature": "states",
                    "type": "topojson"
                }
            },
            "encoding": {
                "color": {
                    "value": "#eee"
                }
            }
        },
        {
            "mark": "circle",
            "data": {
                "url": "https://vega.github.io/vega-lite/data/airports.csv"
            },
            "encoding": {
                "color": {
                    "value": "gray"
                },
                "size": {
                    "value": 5
                },
                "latitude": {
                    "field": "latitude",
                    "type": "quantitative"
                },
                "longitude": {
                    "field": "longitude",
                    "type": "quantitative"
                }
            }
        },
        {
            "transform": [
                {
                    "filter": {
                        "equal": "SEA",
                        "field": "origin"
                    }
                },
                {
                    "from": {
                        "data": {
                            "url": "https://vega.github.io/vega-lite/data/airports.csv"
                        },
                        "key": "iata",
                        "fields": [
                            "latitude",
                            "longitude"
                        ]
                    },
                    "lookup": "origin"
                },
                {
                    "as": "origin_latitude",
                    "calculate": "datum.latitude"
                },
                {
                    "as": "origin_longitude",
                    "calculate": "datum.longitude"
                },
                {
                    "from": {
                        "data": {
                            "url": "https://vega.github.io/vega-lite/data/airports.csv"
                        },
                        "key": "iata",
                        "fields": [
                            "latitude",
                            "longitude"
                        ]
                    },
                    "lookup": "destination"
                },
                {
                    "as": "dest_latitude",
                    "calculate": "datum.latitude"
                },
                {
                    "as": "dest_longitude",
                    "calculate": "datum.longitude"
                }
            ],
            "mark": "rule",
            "data": {
                "url": "https://vega.github.io/vega-lite/data/flights-airport.csv"
            },
            "encoding": {
                "latitude": {
                    "field": "origin_latitude",
                    "type": "quantitative"
                },
                "latitude2": {
                    "field": "dest_latitude"
                },
                "longitude": {
                    "field": "origin_longitude",
                    "type": "quantitative"
                },
                "longitude2": {
                    "field": "dest_longitude"
                }
            }
        }
    ],
    "description": "Rules (line segments) connecting SEA to every airport reachable via direct flight"
}