area_gradient.vg.json

{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "description": "Google's stock price over time.",
  "background": "white",
  "padding": 5,
  "width": 200,
  "height": 200,
  "style": "cell",
  "data": [
    {
      "name": "source_0",
      "url": "data/stocks.csv",
      "format": {"type": "csv", "parse": {"date": "date"}},
      "transform": [
        {"type": "filter", "expr": "datum.symbol==='GOOG'"},
        {
          "type": "impute",
          "field": "price",
          "groupby": [],
          "key": "date",
          "method": "value",
          "value": 0
        },
        {
          "type": "stack",
          "groupby": ["date"],
          "field": "price",
          "sort": {"field": [], "order": []},
          "as": ["price_start", "price_end"],
          "offset": "zero"
        }
      ]
    }
  ],
  "marks": [
    {
      "name": "layer_0_marks",
      "type": "area",
      "style": ["area"],
      "sort": {"field": "datum[\"date\"]"},
      "from": {"data": "source_0"},
      "encode": {
        "update": {
          "opacity": {"value": 0.7},
          "orient": {"value": "vertical"},
          "fill": {
            "value": {
              "x1": 1,
              "y1": 1,
              "x2": 1,
              "y2": 0,
              "gradient": "linear",
              "stops": [
                {"offset": 0, "color": "white"},
                {"offset": 1, "color": "darkgreen"}
              ]
            }
          },
          "description": {
            "signal": "\"date: \" + (timeFormat(datum[\"date\"], '%b %d, %Y')) + \"; price: \" + (format(datum[\"price\"], \"\"))"
          },
          "x": {"scale": "x", "field": "date"},
          "y": {"scale": "y", "field": "price_end"},
          "y2": {"scale": "y", "field": "price_start"},
          "defined": {
            "signal": "isValid(datum[\"date\"]) && isFinite(+datum[\"date\"]) && isValid(datum[\"price\"]) && isFinite(+datum[\"price\"])"
          }
        }
      }
    },
    {
      "name": "layer_1_marks",
      "type": "line",
      "style": ["line"],
      "sort": {"field": "datum[\"date\"]"},
      "from": {"data": "source_0"},
      "encode": {
        "update": {
          "stroke": {"value": "darkgreen"},
          "description": {
            "signal": "\"date: \" + (timeFormat(datum[\"date\"], '%b %d, %Y')) + \"; price: \" + (format(datum[\"price\"], \"\"))"
          },
          "x": {"scale": "x", "field": "date"},
          "y": {"scale": "y", "field": "price_end"},
          "defined": {
            "signal": "isValid(datum[\"date\"]) && isFinite(+datum[\"date\"]) && isValid(datum[\"price\"]) && isFinite(+datum[\"price\"])"
          }
        }
      }
    }
  ],
  "scales": [
    {
      "name": "x",
      "type": "time",
      "domain": {"data": "source_0", "field": "date"},
      "range": [0, {"signal": "width"}]
    },
    {
      "name": "y",
      "type": "linear",
      "domain": {"data": "source_0", "fields": ["price_start", "price_end"]},
      "range": [{"signal": "height"}, 0],
      "nice": true,
      "zero": true
    }
  ],
  "axes": [
    {
      "scale": "x",
      "orient": "bottom",
      "gridScale": "y",
      "grid": true,
      "tickCount": {"signal": "ceil(width/40)"},
      "domain": false,
      "labels": false,
      "aria": false,
      "maxExtent": 0,
      "minExtent": 0,
      "ticks": false,
      "zindex": 0
    },
    {
      "scale": "y",
      "orient": "left",
      "gridScale": "x",
      "grid": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "domain": false,
      "labels": false,
      "aria": false,
      "maxExtent": 0,
      "minExtent": 0,
      "ticks": false,
      "zindex": 0
    },
    {
      "scale": "x",
      "orient": "bottom",
      "grid": false,
      "title": "date",
      "labelFlush": true,
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(width/40)"},
      "zindex": 0
    },
    {
      "scale": "y",
      "orient": "left",
      "grid": false,
      "title": "price",
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "zindex": 0
    }
  ]
}