{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "description": "The population of the German city of Falkensee over time",
  "background": "white",
  "padding": 5,
  "width": 500,
  "height": 200,
  "style": "cell",
  "data": [
    {
      "name": "source_0",
      "values": [
        {"year": "1875", "population": 1309},
        {"year": "1890", "population": 1558},
        {"year": "1910", "population": 4512},
        {"year": "1925", "population": 8180},
        {"year": "1933", "population": 15915},
        {"year": "1939", "population": 24824},
        {"year": "1946", "population": 28275},
        {"year": "1950", "population": 29189},
        {"year": "1964", "population": 29881},
        {"year": "1971", "population": 26007},
        {"year": "1981", "population": 24029},
        {"year": "1985", "population": 23340},
        {"year": "1989", "population": 22307},
        {"year": "1990", "population": 22087},
        {"year": "1991", "population": 22139},
        {"year": "1992", "population": 22105},
        {"year": "1993", "population": 22242},
        {"year": "1994", "population": 22801},
        {"year": "1995", "population": 24273},
        {"year": "1996", "population": 25640},
        {"year": "1997", "population": 27393},
        {"year": "1998", "population": 29505},
        {"year": "1999", "population": 32124},
        {"year": "2000", "population": 33791},
        {"year": "2001", "population": 35297},
        {"year": "2002", "population": 36179},
        {"year": "2003", "population": 36829},
        {"year": "2004", "population": 37493},
        {"year": "2005", "population": 38376},
        {"year": "2006", "population": 39008},
        {"year": "2007", "population": 39366},
        {"year": "2008", "population": 39821},
        {"year": "2009", "population": 40179},
        {"year": "2010", "population": 40511},
        {"year": "2011", "population": 40465},
        {"year": "2012", "population": 40905},
        {"year": "2013", "population": 41258},
        {"year": "2014", "population": 41777}
      ]
    },
    {
      "name": "source_1",
      "values": [
        {"start": "1933", "end": "1945", "event": "Nazi Rule"},
        {"start": "1948", "end": "1989", "event": "GDR (East Germany)"}
      ]
    },
    {
      "name": "data_0",
      "source": "source_0",
      "transform": [
        {
          "type": "formula",
          "expr": "timeParse(datum[\"year\"],'%Y')",
          "as": "year"
        },
        {
          "field": "year",
          "type": "timeunit",
          "units": ["year"],
          "as": ["year_year", "year_year_end"]
        }
      ]
    },
    {
      "name": "data_1",
      "source": "data_0",
      "transform": [
        {
          "type": "filter",
          "expr": "(isDate(datum[\"year_year\"]) || (isValid(datum[\"year_year\"]) && isFinite(+datum[\"year_year\"]))) && isValid(datum[\"population\"]) && isFinite(+datum[\"population\"])"
        }
      ]
    },
    {
      "name": "data_2",
      "source": "source_1",
      "transform": [
        {
          "type": "formula",
          "expr": "timeParse(datum[\"start\"],'%Y')",
          "as": "start"
        },
        {
          "type": "formula",
          "expr": "timeParse(datum[\"end\"],'%Y')",
          "as": "end"
        },
        {
          "field": "start",
          "type": "timeunit",
          "units": ["year"],
          "as": ["year_start", "year_start_end"]
        },
        {
          "field": "end",
          "type": "timeunit",
          "units": ["year"],
          "as": ["year_end", "year_end_end"]
        },
        {
          "type": "filter",
          "expr": "(isDate(datum[\"year_start\"]) || (isValid(datum[\"year_start\"]) && isFinite(+datum[\"year_start\"])))"
        }
      ]
    }
  ],
  "marks": [
    {
      "name": "layer_0_marks",
      "type": "rect",
      "style": ["rect"],
      "from": {"data": "data_2"},
      "encode": {
        "update": {
          "fill": {"scale": "color", "field": "event"},
          "description": {
            "signal": "\"start (year): \" + (timeFormat(datum[\"year_start\"], timeUnitSpecifier([\"year\"], {\"year-month\":\"%b %Y \",\"year-month-date\":\"%b %d, %Y \"}))) + \"; end (year): \" + (timeFormat(datum[\"year_end\"], timeUnitSpecifier([\"year\"], {\"year-month\":\"%b %Y \",\"year-month-date\":\"%b %d, %Y \"}))) + \"; event: \" + (isValid(datum[\"event\"]) ? datum[\"event\"] : \"\"+datum[\"event\"])"
          },
          "x": {"scale": "x", "field": "year_start"},
          "x2": {"scale": "x", "field": "year_end"},
          "y": {"value": 0},
          "y2": {"field": {"group": "height"}}
        }
      }
    },
    {
      "name": "layer_1_marks",
      "type": "line",
      "style": ["line"],
      "sort": {"field": "datum[\"year_year\"]"},
      "from": {"data": "data_0"},
      "encode": {
        "update": {
          "stroke": {"value": "#333"},
          "description": {
            "signal": "\"year (year): \" + (timeFormat(datum[\"year_year\"], timeUnitSpecifier([\"year\"], {\"year-month\":\"%b %Y \",\"year-month-date\":\"%b %d, %Y \"}))) + \"; population: \" + (format(datum[\"population\"], \"\"))"
          },
          "x": {"scale": "x", "field": "year_year"},
          "y": {"scale": "y", "field": "population"},
          "defined": {
            "signal": "isValid(datum[\"year_year\"]) && isFinite(+datum[\"year_year\"]) && isValid(datum[\"population\"]) && isFinite(+datum[\"population\"])"
          }
        }
      }
    },
    {
      "name": "layer_2_marks",
      "type": "symbol",
      "style": ["point"],
      "from": {"data": "data_1"},
      "encode": {
        "update": {
          "opacity": {"value": 0.7},
          "fill": {"value": "transparent"},
          "stroke": {"value": "#333"},
          "ariaRoleDescription": {"value": "point"},
          "description": {
            "signal": "\"year (year): \" + (timeFormat(datum[\"year_year\"], timeUnitSpecifier([\"year\"], {\"year-month\":\"%b %Y \",\"year-month-date\":\"%b %d, %Y \"}))) + \"; population: \" + (format(datum[\"population\"], \"\"))"
          },
          "x": {"scale": "x", "field": "year_year"},
          "y": {"scale": "y", "field": "population"}
        }
      }
    }
  ],
  "scales": [
    {
      "name": "x",
      "type": "time",
      "domain": {
        "fields": [
          {"data": "data_2", "field": "year_start"},
          {"data": "data_2", "field": "year_end"},
          {"data": "data_0", "field": "year_year"},
          {"data": "data_1", "field": "year_year"}
        ]
      },
      "range": [0, {"signal": "width"}]
    },
    {
      "name": "color",
      "type": "ordinal",
      "domain": {"data": "data_2", "field": "event", "sort": true},
      "range": "category"
    },
    {
      "name": "y",
      "type": "linear",
      "domain": {
        "fields": [
          {"data": "data_0", "field": "population"},
          {"data": "data_1", "field": "population"}
        ]
      },
      "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": "year (year)",
      "format": {
        "signal": "timeUnitSpecifier([\"year\"], {\"year-month\":\"%b %Y \",\"year-month-date\":\"%b %d, %Y \"})"
      },
      "labelFlush": true,
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(width/40)"},
      "zindex": 0
    },
    {
      "scale": "y",
      "orient": "left",
      "grid": false,
      "title": "population",
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "zindex": 0
    }
  ],
  "legends": [{"fill": "color", "symbolType": "square", "title": "event"}]
}