Vega view for a visualisation of Work Horses vs Tractors

farm-survey.json

{
  "width": 800,
  "height": 200,
  "data": [
    {
      "name": "farm-survey",
      "url": "https://gist.githubusercontent.com/brew/9cd259fda775ad3f7713ca8f2b623aaa/raw/e8c4dc4b2af82032d1c1ffd42ecd6acc2484a74a/farm-survey",
      "format": {
        "type": "csv",
        "parse": {
          "Year": "integer",
          "WorkHorses": "number",
          "Tractor": "number"
        }
      },
      "transform": [
        {
          "type": "aggregate",
          "groupby": ["Year"],
          "summarize": [
            {
              "field": "WorkHorses",
              "ops": ["sum"],
              "as": ["workhorses_sum"]
            },
            {
              "field": "Tractor",
              "ops": ["sum"],
              "as": ["tractor_sum"]
            }
          ]
        }
      ]
    }
  ],
  "scales": [
    {
      "name": "x",
      "type": "linear",
      "range": "width",
      "zero": false,
      "domainMin": 1938,
      "domainMax": 1986,
      "domain": {"data": "farm-survey","field": "Year"}
    },
    {
      "name": "y",
      "type": "linear",
      "range": "height",
      "nice": true,
      "domain": {"data": "farm-survey","field": "tractor_sum"}
    }
  ],
  "axes": [
    {"type": "x","scale": "x","format": "04d"},
    {"type": "y","scale": "y"}
  ],
  "marks": [
    {
      "type": "rect",
      "from": {"data": "farm-survey"},
      "properties": {
        "enter": {
          "x": {"scale": "x", "field": "Year"},
          "width": {"value": 15},
          "y": {"scale": "y", "field": "tractor_sum"},
          "y2": {"scale": "y", "value": 0},
          "fill": {"value": "#B3D9E6"},
          "strokeWidth": {"value": 0.25}
        }
      }
    },
    {
      "type": "rect",
      "from": {"data": "farm-survey"},
      "properties": {
        "enter": {
          "x": {"scale": "x", "field": "Year"},
          "width": {"value": 15},
          "y": {"scale": "y", "field": "workhorses_sum"},
          "y2": {"scale": "y", "value": 0},
          "fill": {"value": "#aaa"},
          "fillOpacity": {"value": 0.5},
          "strokeWidth": {"value": 0.25}
        }
      }
    }    
  ]
}