linecolorhalo.vl

{
    "$schema": "https://vega.github.io/schema/vega-lite/v4.json",
    "data": {
        "url": "https://vega.github.io/vega-lite/data/stocks.csv"
    },
    "description": "Multi-series Line Chart with Halo. Use pivot and repeat-layer as a workaround to facet groups of lines and their halo strokes. See https://github.com/vega/vega-lite/issues/6192 for more discussion.",
    "repeat": {
        "layer": [
            "AAPL",
            "AMZN",
            "GOOG",
            "IBM",
            "MSFT"
        ]
    },
    "spec": {
        "layer": [
            {
                "encoding": {
                    "x": {
                        "field": "date",
                        "type": "temporal"
                    },
                    "y": {
                        "field": {
                            "repeat": "layer"
                        },
                        "title": "price",
                        "type": "quantitative"
                    }
                },
                "mark": {
                    "stroke": "white",
                    "strokeWidth": 4,
                    "type": "line"
                }
            },
            {
                "encoding": {
                    "stroke": {
                        "datum": {
                            "repeat": "layer"
                        },
                        "type": "nominal"
                    },
                    "x": {
                        "field": "date",
                        "type": "temporal"
                    },
                    "y": {
                        "field": {
                            "repeat": "layer"
                        },
                        "title": "price",
                        "type": "quantitative"
                    }
                },
                "mark": "line"
            }
        ]
    },
    "transform": [
        {
            "groupby": [
                "date"
            ],
            "pivot": "symbol",
            "value": "price"
        }
    ]
}