{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "description": "A trellis bar chart showing the US population distribution of age groups and gender in 2000.",
  "background": "white",
  "padding": 5,
  "data": [
    {
      "name": "source_0",
      "url": "data/population.json",
      "format": {"type": "json"},
      "transform": [
        {"type": "filter", "expr": "datum.year == 2000"},
        {
          "type": "formula",
          "expr": "datum.sex == 2 ? 'Female' : 'Male'",
          "as": "gender"
        },
        {
          "type": "aggregate",
          "groupby": ["age", "gender"],
          "ops": ["sum"],
          "fields": ["people"],
          "as": ["sum_people"]
        },
        {
          "type": "stack",
          "groupby": ["age", "gender"],
          "field": "sum_people",
          "sort": {"field": ["gender"], "order": ["descending"]},
          "as": ["sum_people_start", "sum_people_end"],
          "offset": "zero"
        },
        {
          "type": "filter",
          "expr": "isValid(datum[\"sum_people\"]) && isFinite(+datum[\"sum_people\"])"
        }
      ]
    },
    {
      "name": "row_domain",
      "source": "source_0",
      "transform": [{"type": "aggregate", "groupby": ["gender"]}]
    }
  ],
  "signals": [
    {"name": "x_step", "value": 17},
    {
      "name": "child_width",
      "update": "bandspace(domain('x').length, 0.1, 0.05) * x_step"
    },
    {"name": "child_height", "value": 200}
  ],
  "layout": {"padding": 20, "columns": 1, "bounds": "full", "align": "all"},
  "marks": [
    {
      "name": "row_header",
      "type": "group",
      "role": "row-header",
      "from": {"data": "row_domain"},
      "sort": {"field": "datum[\"gender\"]", "order": "ascending"},
      "encode": {"update": {"height": {"signal": "child_height"}}},
      "axes": [
        {
          "scale": "y",
          "orient": "left",
          "grid": false,
          "title": "population",
          "labelOverlap": true,
          "tickCount": {"signal": "ceil(child_height/40)"},
          "zindex": 0
        }
      ]
    },
    {
      "name": "column_footer",
      "type": "group",
      "role": "column-footer",
      "encode": {"update": {"width": {"signal": "child_width"}}},
      "axes": [
        {
          "scale": "x",
          "orient": "bottom",
          "grid": false,
          "title": "age",
          "labelAlign": "right",
          "labelAngle": 270,
          "labelBaseline": "middle",
          "zindex": 0
        }
      ]
    },
    {
      "name": "cell",
      "type": "group",
      "style": "cell",
      "from": {
        "facet": {"name": "facet", "data": "source_0", "groupby": ["gender"]}
      },
      "sort": {"field": ["datum[\"gender\"]"], "order": ["ascending"]},
      "encode": {
        "update": {
          "width": {"signal": "child_width"},
          "height": {"signal": "child_height"}
        }
      },
      "marks": [
        {
          "name": "child_marks",
          "type": "rect",
          "style": ["bar"],
          "from": {"data": "facet"},
          "encode": {
            "update": {
              "fill": {"scale": "color", "field": "gender"},
              "ariaRoleDescription": {"value": "bar"},
              "description": {
                "signal": "\"age: \" + (isValid(datum[\"age\"]) ? datum[\"age\"] : \"\"+datum[\"age\"]) + \"; population: \" + (format(datum[\"sum_people\"], \"\")) + \"; gender: \" + (isValid(datum[\"gender\"]) ? datum[\"gender\"] : \"\"+datum[\"gender\"])"
              },
              "x": {"scale": "x", "field": "age"},
              "width": {"scale": "x", "band": 1},
              "y": {"scale": "y", "field": "sum_people_end"},
              "y2": {"scale": "y", "field": "sum_people_start"}
            }
          }
        }
      ],
      "axes": [
        {
          "scale": "y",
          "orient": "left",
          "gridScale": "x",
          "grid": true,
          "tickCount": {"signal": "ceil(child_height/40)"},
          "domain": false,
          "labels": false,
          "aria": false,
          "maxExtent": 0,
          "minExtent": 0,
          "ticks": false,
          "zindex": 0
        }
      ]
    }
  ],
  "scales": [
    {
      "name": "x",
      "type": "band",
      "domain": {"data": "source_0", "field": "age", "sort": true},
      "range": {"step": {"signal": "x_step"}},
      "paddingInner": 0.1,
      "paddingOuter": 0.05
    },
    {
      "name": "y",
      "type": "linear",
      "domain": {
        "data": "source_0",
        "fields": ["sum_people_start", "sum_people_end"]
      },
      "range": [{"signal": "child_height"}, 0],
      "nice": true,
      "zero": true
    },
    {
      "name": "color",
      "type": "ordinal",
      "domain": {"data": "source_0", "field": "gender", "sort": true},
      "range": ["#675193", "#ca8861"]
    }
  ],
  "legends": [{"fill": "color", "symbolType": "square", "title": "gender"}]
}