line2.vl

{
    "transform": [
        {
            "filter": "datum.symbol === 'GOOG'"
        }
    ],
    "mark": {
        "color": "green",
        "point": {
            "color": "purple"
        },
        "type": "line"
    },
    "data": {
        "url": "https://vega.github.io/vega-lite/data/stocks.csv"
    },
    "$schema": "https://vega.github.io/schema/vega-lite/v3.json",
    "encoding": {
        "x": {
            "field": "date",
            "type": "temporal",
            "axis": {
                "format": "%Y"
            }
        },
        "y": {
            "field": "price",
            "type": "quantitative"
        }
    },
    "description": "Google's stock price over time with point markers."
}