pivot1.vl

{
    "$schema": "https://vega.github.io/schema/vega-lite/v4.json",
    "repeat": [
        "gold",
        "silver"
    ],
    "spec": {
        "data": {
            "values": [
                {
                    "count": 10,
                    "country": "USA",
                    "medalType": "gold"
                },
                {
                    "count": 20,
                    "country": "USA",
                    "medalType": "silver"
                },
                {
                    "count": 7,
                    "country": "Canada",
                    "medalType": "gold"
                },
                {
                    "count": 26,
                    "country": "Canada",
                    "medalType": "silver"
                }
            ]
        },
        "encoding": {
            "color": {
                "field": "country",
                "type": "nominal"
            },
            "x": {
                "field": "country",
                "type": "nominal"
            },
            "y": {
                "field": {
                    "repeat": "repeat"
                },
                "type": "quantitative"
            }
        },
        "mark": "bar",
        "transform": [
            {
                "groupby": [
                    "country"
                ],
                "pivot": "medalType",
                "value": "count"
            }
        ]
    }
}