{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "description": "Interactive cross-filtering among histograms of flight statistics.",
  "width": 500,
  "padding": 5,

  "signals": [
    { "name": "chartHeight", "value": 100 },
    { "name": "chartPadding", "value": 50 },
    { "name": "height", "update": "(chartHeight + chartPadding) * 3" },
    { "name": "delayExtent", "value": [-60, 180] },
    { "name": "timeExtent", "value": [0, 24] },
    { "name": "distExtent", "value": [0, 2400] },
    { "name": "delayStep", "value": 10,
      "bind": {"input": "range", "min": 2, "max": 20, "step": 1} },
    { "name": "timeStep", "value": 1,
      "bind": {"input": "range", "min": 0.25, "max": 2, "step": 0.25} },
    { "name": "distStep", "value": 100,
      "bind": {"input": "range", "min": 50, "max": 200, "step": 50} },
    { "name": "delayRange", "update": "delayExtent",
      "on": [
        {
          "events": {"signal": "delayZoom"},
          "update": "[(delayRange[0]+delayRange[1])/2 - delayZoom, (delayRange[0]+delayRange[1])/2 + delayZoom]"
        },
        {
          "events": "@delay:dblclick!, @delayBrush:dblclick!",
          "update": "[delayExtent[0], delayExtent[1]]"
        },
        {
          "events": "[@delayBrush:pointerdown, window:pointerup] > window:pointermove!",
          "update": "[delayRange[0] + invert('delayScale', x()) - invert('delayScale', xmove), delayRange[1] + invert('delayScale', x()) - invert('delayScale', xmove)]"
        },
        {
          "events": "[@delay:pointerdown, window:pointerup] > window:pointermove!",
          "update": "[min(delayAnchor, invert('delayScale', x())), max(delayAnchor, invert('delayScale', x()))]"
        }
      ]
    },
    { "name": "delayZoom", "value": 0,
      "on": [{
        "events": "@delay:wheel!, @delayBrush:wheel!",
        "update": "0.5 * abs(span(delayRange)) * pow(1.0005, event.deltaY * pow(16, event.deltaMode))"
      }]
    },
    { "name": "delayAnchor", "value": 0,
      "on": [{
        "events": "@delay:pointerdown!",
        "update": "invert('delayScale', x())"}
      ]
    },
    { "name": "timeRange", "update": "timeExtent",
      "on": [
        {
          "events": {"signal": "timeZoom"},
          "update": "[(timeRange[0]+timeRange[1])/2 - timeZoom, (timeRange[0]+timeRange[1])/2 + timeZoom]"
        },
        {
          "events": "@time:dblclick!, @timeBrush:dblclick!",
          "update": "[timeExtent[0], timeExtent[1]]"
        },
        {
          "events": "[@timeBrush:pointerdown, window:pointerup] > window:pointermove!",
          "update": "[timeRange[0] + invert('timeScale', x()) - invert('timeScale', xmove), timeRange[1] + invert('timeScale', x()) - invert('timeScale', xmove)]"
        },
        {
          "events": "[@time:pointerdown, window:pointerup] > window:pointermove!",
          "update": "[min(timeAnchor, invert('timeScale', x())), max(timeAnchor, invert('timeScale', x()))]"
        }
      ]
    },
    { "name": "timeZoom", "value": 0,
      "on": [{
        "events": "@time:wheel!, @timeBrush:wheel!",
        "update": "0.5 * abs(span(timeRange)) * pow(1.0005, event.deltaY * pow(16, event.deltaMode))"
      }]
    },
    { "name": "timeAnchor", "value": 0,
      "on": [{
        "events": "@time:pointerdown!",
        "update": "invert('timeScale', x())"}
      ]
    },
    { "name": "distRange", "update": "distExtent",
      "on": [
        {
          "events": {"signal": "distZoom"},
          "update": "[(distRange[0]+distRange[1])/2 - distZoom, (distRange[0]+distRange[1])/2 + distZoom]"
        },
        {
          "events": "@dist:dblclick!, @distBrush:dblclick!",
          "update": "[distExtent[0], distExtent[1]]"
        },
        {
          "events": "[@distBrush:pointerdown, window:pointerup] > window:pointermove!",
          "update": "[distRange[0] + invert('distScale', x()) - invert('distScale', xmove), distRange[1] + invert('distScale', x()) - invert('distScale', xmove)]"
        },
        {
          "events": "[@dist:pointerdown, window:pointerup] > window:pointermove!",
          "update": "[min(distAnchor, invert('distScale', x())), max(distAnchor, invert('distScale', x()))]"
        }
      ]
    },
    { "name": "distZoom", "value": 0,
      "on": [{
        "events": "@dist:wheel!, @distBrush:wheel!",
        "update": "0.5 * abs(span(distRange)) * pow(1.0005, event.deltaY * pow(16, event.deltaMode))"
      }]
    },
    { "name": "distAnchor", "value": 0,
      "on": [{
        "events": "@dist:pointerdown!",
        "update": "invert('distScale', x())"}
      ]
    },
    { "name": "xmove", "value": 0,
      "on": [{"events": "window:pointermove", "update": "x()"}]
    }
  ],

  "data": [
    {
      "name": "flights",
      "url": "data/flights-200k.json",
      "transform": [
        {
          "type": "bin", "field": "delay",
          "extent": {"signal": "delayExtent"},
          "step": {"signal": "delayStep"},
          "as": ["delay0", "delay1"]
        },
        {
          "type": "bin", "field": "time",
          "extent": {"signal": "timeExtent"},
          "step": {"signal": "timeStep"},
          "as": ["time0", "time1"]
        },
        {
          "type": "bin", "field": "distance",
          "extent": {"signal": "distExtent"},
          "step": {"signal": "distStep"},
          "as": ["dist0", "dist1"]
        },
        {
          "type": "crossfilter",
          "signal": "xfilter",
          "fields": ["delay", "time", "distance"],
          "query": [
            {"signal": "delayRange"},
            {"signal": "timeRange"},
            {"signal": "distRange"}
          ]
        }
      ]
    }
  ],

  "scales": [
    {
      "name": "layout",
      "type": "band",
      "domain": ["delay", "time", "distance"],
      "range": "height"
    },
    {
      "name": "delayScale",
      "type": "linear",
      "round": true,
      "domain": {"signal": "delayExtent"},
      "range": "width"
    },
    {
      "name": "timeScale",
      "type": "linear",
      "round": true,
      "domain": {"signal": "timeExtent"},
      "range": "width"
    },
    {
      "name": "distScale",
      "type": "linear",
      "round": true,
      "domain": {"signal": "distExtent"},
      "range": "width"
    }
  ],

  "marks": [
    {
      "description": "Delay Histogram",
      "name": "delay",
      "type": "group",
      "encode": {
        "enter": {
          "y": {"scale": "layout", "value": "delay", "offset": 20},
          "width": {"signal": "width"},
          "height": {"signal": "chartHeight"},
          "fill": {"value": "transparent"}
        }
      },

      "data": [
        {
          "name": "delay-bins",
          "source": "flights",
          "transform": [
            {
              "type": "resolvefilter",
              "ignore": 1,
              "filter": {"signal": "xfilter"}
            },
            {
              "type": "aggregate",
              "groupby": ["delay0", "delay1"],
              "key": "delay0", "drop": false
            }
          ]
        }
      ],

      "scales": [
        {
          "name": "yscale",
          "type": "linear",
          "domain": {"data": "delay-bins", "field": "count"},
          "range": [{"signal": "chartHeight"}, 0]
        }
      ],

      "axes": [
        {"orient": "bottom", "scale": "delayScale"}
      ],

      "marks": [
        {
          "type": "rect",
          "name": "delayBrush",
          "encode": {
            "enter": {
              "y": {"value": 0},
              "height": {"signal": "chartHeight"},
              "fill": {"value": "#fcfcfc"}
            },
            "update": {
              "x": {"signal": "scale('delayScale', delayRange[0])"},
              "x2": {"signal": "scale('delayScale', delayRange[1])"}
            }
          }
        },
        {
          "type": "rect",
          "interactive": false,
          "from": {"data": "delay-bins"},
          "encode": {
            "enter": {
              "fill": {"value": "steelblue"}
            },
            "update": {
              "x": {"scale": "delayScale", "field": "delay0"},
              "x2": {"scale": "delayScale", "field": "delay1", "offset": -1},
              "y": {"scale": "yscale", "field": "count"},
              "y2": {"scale": "yscale", "value": 0}
            }
          }
        },
        {
          "type": "rect",
          "interactive": false,
          "encode": {
            "enter": {
              "y": {"value": 0},
              "height": {"signal": "chartHeight"},
              "fill": {"value": "firebrick"}
            },
            "update": {
              "x": {"signal": "scale('delayScale', delayRange[0])"},
              "width": {"value": 1}
            }
          }
        },
        {
          "type": "rect",
          "interactive": false,
          "encode": {
            "enter": {
              "y": {"value": 0},
              "height": {"signal": "chartHeight"},
              "fill": {"value": "firebrick"}
            },
            "update": {
              "x": {"signal": "scale('delayScale', delayRange[1])"},
              "width": {"value": 1}
            }
          }
        },
        {
          "type": "text",
          "interactive": false,
          "encode": {
            "enter": {
              "y": {"value": -5},
              "text": {"value": "Arrival Delay (min)"},
              "baseline": {"value": "bottom"},
              "fontSize": {"value": 14},
              "fontWeight": {"value": 500},
              "fill": {"value": "black"}
            }
          }
        }
      ]
    },

    {
      "description": "Time Histogram",
      "name": "time",
      "type": "group",
      "encode": {
        "enter": {
          "y": {"scale": "layout", "value": "time", "offset": 20},
          "width": {"signal": "width"},
          "height": {"signal": "chartHeight"},
          "fill": {"value": "transparent"}
        }
      },

      "data": [
        {
          "name": "time-bins",
          "source": "flights",
          "transform": [
            {
              "type": "resolvefilter",
              "ignore": 2,
              "filter": {"signal": "xfilter"}
            },
            {
              "type": "aggregate",
              "groupby": ["time0", "time1"],
              "key": "time0", "drop": false
            }
          ]
        }
      ],

      "scales": [
        {
          "name": "yscale",
          "type": "linear",
          "domain": {"data": "time-bins", "field": "count"},
          "range": [{"signal": "chartHeight"}, 0]
        }
      ],

      "axes": [
        {"orient": "bottom", "scale": "timeScale"}
      ],

      "marks": [
        {
          "type": "rect",
          "name": "timeBrush",
          "encode": {
            "enter": {
              "y": {"value": 0},
              "height": {"signal": "chartHeight"},
              "fill": {"value": "#fcfcfc"}
            },
            "update": {
              "x": {"signal": "scale('timeScale', timeRange[0])"},
              "x2": {"signal": "scale('timeScale', timeRange[1])"}
            }
          }
        },
        {
          "type": "rect",
          "from": {"data": "time-bins"},
          "interactive": false,
          "encode": {
            "enter": {
              "fill": {"value": "steelblue"}
            },
            "update": {
              "x": {"scale": "timeScale", "field": "time0"},
              "x2": {"scale": "timeScale", "field": "time1", "offset": -1},
              "y": {"scale": "yscale", "field": "count"},
              "y2": {"scale": "yscale", "value": 0}
            }
          }
        },
        {
          "type": "rect",
          "interactive": false,
          "encode": {
            "enter": {
              "y": {"value": 0},
              "height": {"signal": "chartHeight"},
              "fill": {"value": "firebrick"}
            },
            "update": {
              "x": {"signal": "scale('timeScale', timeRange[0])"},
              "width": {"value": 1}
            }
          }
        },
        {
          "type": "rect",
          "interactive": false,
          "encode": {
            "enter": {
              "y": {"value": 0},
              "height": {"signal": "chartHeight"},
              "fill": {"value": "firebrick"}
            },
            "update": {
              "x": {"signal": "scale('timeScale', timeRange[1])"},
              "width": {"value": 1}
            }
          }
        },
        {
          "type": "text",
          "interactive": false,
          "encode": {
            "enter": {
              "y": {"value": -5},
              "text": {"value": "Local Departure Time (hour)"},
              "baseline": {"value": "bottom"},
              "fontSize": {"value": 14},
              "fontWeight": {"value": 500},
              "fill": {"value": "black"}
            }
          }
        }
      ]
    },

    {
      "description": "Distance Histogram",
      "name": "dist",
      "type": "group",
      "encode": {
        "enter": {
          "y": {"scale": "layout", "value": "distance", "offset": 20},
          "width": {"signal": "width"},
          "height": {"signal": "chartHeight"},
          "fill": {"value": "transparent"}
        }
      },

      "data": [
        {
          "name": "dist-bins",
          "source": "flights",
          "transform": [
            {
              "type": "resolvefilter",
              "ignore": 4,
              "filter": {"signal": "xfilter"}
            },
            {
              "type": "aggregate",
              "groupby": ["dist0", "dist1"],
              "key": "dist0", "drop": false
            }
          ]
        }
      ],

      "scales": [
        {
          "name": "yscale",
          "type": "linear",
          "domain": {"data": "dist-bins", "field": "count"},
          "range": [{"signal": "chartHeight"}, 0]
        }
      ],

      "axes": [
        {"orient": "bottom", "scale": "distScale"}
      ],

      "marks": [
        {
          "type": "rect",
          "name": "distBrush",
          "encode": {
            "enter": {
              "y": {"value": 0},
              "height": {"signal": "chartHeight"},
              "fill": {"value": "#fcfcfc"}
            },
            "update": {
              "x": {"signal": "scale('distScale', distRange[0])"},
              "x2": {"signal": "scale('distScale', distRange[1])"}
            }
          }
        },
        {
          "type": "rect",
          "interactive": false,
          "from": {"data": "dist-bins"},
          "encode": {
            "enter": {
              "fill": {"value": "steelblue"}
            },
            "update": {
              "x": {"scale": "distScale", "field": "dist0"},
              "x2": {"scale": "distScale", "field": "dist1", "offset": -1},
              "y": {"scale": "yscale", "field": "count"},
              "y2": {"scale": "yscale", "value": 0}
            }
          }
        },
        {
          "type": "rect",
          "interactive": false,
          "encode": {
            "enter": {
              "y": {"value": 0},
              "height": {"signal": "chartHeight"},
              "fill": {"value": "firebrick"}
            },
            "update": {
              "x": {"signal": "scale('distScale', distRange[0])"},
              "width": {"value": 1}
            }
          }
        },
        {
          "type": "rect",
          "interactive": false,
          "encode": {
            "enter": {
              "y": {"value": 0},
              "height": {"signal": "chartHeight"},
              "fill": {"value": "firebrick"}
            },
            "update": {
              "x": {"signal": "scale('distScale', distRange[1])"},
              "width": {"value": 1}
            }
          }
        },
        {
          "type": "text",
          "interactive": false,
          "encode": {
            "enter": {
              "y": {"value": -5},
              "text": {"value": "Travel Distance (miles)"},
              "baseline": {"value": "bottom"},
              "fontSize": {"value": 14},
              "fontWeight": {"value": 500},
              "fill": {"value": "black"}
            }
          }
        }
      ]
    }
  ]
}
