Diverging Stacked Bar Chart (Population Pyramid)

A population pyramid for the US in 2000, created using stack. See https://vega.github.io/vega-lite/examples/concat_population_pyramid.html for a variant of this created using concat.

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Vega-Lite JSON Specification

{
  "$schema": "https://vega.github.io/schema/vega-lite/v3.json",
  "description": "A population pyramid for the US in 2000, created using stack. See https://vega.github.io/vega-lite/examples/concat_population_pyramid.html for a variant of this created using concat.",
  "data": { "url": "data/population.json"},
  "transform": [
    {"filter": "datum.year == 2000"},
    {"calculate": "datum.sex == 2 ? 'Female' : 'Male'", "as": "gender"},
    {"calculate": "datum.sex == 2 ? -datum.people : datum.people", "as": "signed_people"}
  ],
  "width": 300,
  "height": 200,
  "mark": "bar",
  "encoding": {
    "y": {
      "field": "age", "type": "ordinal",
      "axis": null, "sort": "descending"
    },
    "x": {
      "aggregate": "sum", "field": "signed_people", "type": "quantitative",
      "axis": {"title": "population", "format": "s"}
    },
    "color": {
      "field": "gender", "type": "nominal",
      "scale": {"range": ["#e377c2", "#1f77b4"]},
      "legend": {"orient": "top", "title": null}
    }
  },
  "config": {
    "view": {"stroke": null},
    "axis": {"grid": false}
  }
}