{
    "$schema": "https://vega.github.io/schema/vega-lite/v4.json",
    "description": "Drawing rect bin from the beginning of May to end of July",
    "layer": [
        {
            "data": {
                "url": "https://vega.github.io/vega-lite/data/seattle-weather.csv"
            },
            "encoding": {
                "x": {
                    "axis": {
                        "labelAlign": "left",
                        "labelExpr": "datum.label[0]"
                    },
                    "field": "date",
                    "timeUnit": "month",
                    "title": "month",
                    "type": "temporal"
                },
                "y": {
                    "aggregate": "mean",
                    "field": "precipitation",
                    "type": "quantitative"
                }
            },
            "mark": "bar"
        },
        {
            "data": {
                "values": [
                    {
                        "date": "May 1, 2010",
                        "date_end": "July 15, 2010"
                    }
                ]
            },
            "encoding": {
                "x": {
                    "field": "date",
                    "timeUnit": "month",
                    "type": "temporal"
                },
                "x2": {
                    "field": "date_end",
                    "timeUnit": "month"
                }
            },
            "mark": {
                "color": "grey",
                "opacity": 0.5,
                "type": "rect"
            }
        }
    ]
}