{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "background": "white",
  "padding": 5,
  "height": 200,
  "style": "cell",
  "data": [
    {"name": "brush_store"},
    {
      "name": "source_0",
      "url": "https://raw.githubusercontent.com/vega/vega-datasets/master/data/seattle-weather.csv",
      "format": {"type": "csv", "parse": {"date": "date"}, "delimiter": ","},
      "transform": [
        {
          "field": "date",
          "type": "timeunit",
          "units": ["month"],
          "as": ["month_date", "month_date_end"]
        }
      ]
    },
    {
      "name": "data_0",
      "source": "source_0",
      "transform": [
        {
          "type": "filter",
          "expr": "!length(data(\"brush_store\")) || vlSelectionTest(\"brush_store\", datum)"
        },
        {
          "type": "aggregate",
          "groupby": [],
          "ops": ["mean"],
          "fields": ["precipitation"],
          "as": ["mean_precipitation"]
        },
        {
          "type": "filter",
          "expr": "isValid(datum[\"mean_precipitation\"]) && isFinite(+datum[\"mean_precipitation\"])"
        }
      ]
    },
    {
      "name": "data_1",
      "source": "source_0",
      "transform": [
        {
          "type": "aggregate",
          "groupby": ["month_date"],
          "ops": ["mean"],
          "fields": ["precipitation"],
          "as": ["mean_precipitation"]
        },
        {
          "type": "filter",
          "expr": "isValid(datum[\"mean_precipitation\"]) && isFinite(+datum[\"mean_precipitation\"])"
        }
      ]
    }
  ],
  "signals": [
    {"name": "x_step", "value": 20},
    {
      "name": "width",
      "update": "bandspace(domain('x').length, 0.1, 0.05) * x_step"
    },
    {
      "name": "unit",
      "value": {},
      "on": [
        {"events": "mousemove", "update": "isTuple(group()) ? group() : unit"}
      ]
    },
    {
      "name": "brush",
      "update": "vlSelectionResolve(\"brush_store\", \"union\")"
    },
    {
      "name": "brush_x",
      "value": [],
      "on": [
        {
          "events": {
            "source": "scope",
            "type": "mousedown",
            "filter": [
              "!event.item || event.item.mark.name !== \"brush_brush\""
            ]
          },
          "update": "[x(unit), x(unit)]"
        },
        {
          "events": {
            "source": "window",
            "type": "mousemove",
            "consume": true,
            "between": [
              {
                "source": "scope",
                "type": "mousedown",
                "filter": [
                  "!event.item || event.item.mark.name !== \"brush_brush\""
                ]
              },
              {"source": "window", "type": "mouseup"}
            ]
          },
          "update": "[brush_x[0], clamp(x(unit), 0, width)]"
        },
        {"events": {"signal": "brush_scale_trigger"}, "update": "[0, 0]"},
        {
          "events": [{"source": "view", "type": "dblclick"}],
          "update": "[0, 0]"
        },
        {
          "events": {"signal": "brush_translate_delta"},
          "update": "clampRange(panLinear(brush_translate_anchor.extent_x, brush_translate_delta.x / span(brush_translate_anchor.extent_x)), 0, width)"
        },
        {
          "events": {"signal": "brush_zoom_delta"},
          "update": "clampRange(zoomLinear(brush_x, brush_zoom_anchor.x, brush_zoom_delta), 0, width)"
        }
      ]
    },
    {
      "name": "brush_month_date",
      "on": [
        {
          "events": {"signal": "brush_x"},
          "update": "brush_x[0] === brush_x[1] ? null : invert(\"x\", brush_x)"
        }
      ]
    },
    {
      "name": "brush_scale_trigger",
      "value": {},
      "on": [
        {
          "events": [{"scale": "x"}],
          "update": "(!isArray(brush_month_date) || (invert(\"x\", brush_x)[0] === brush_month_date[0] && invert(\"x\", brush_x)[1] === brush_month_date[1])) ? brush_scale_trigger : {}"
        }
      ]
    },
    {
      "name": "brush_tuple",
      "on": [
        {
          "events": [{"signal": "brush_month_date"}],
          "update": "brush_month_date ? {unit: \"layer_0\", fields: brush_tuple_fields, values: [brush_month_date]} : null"
        }
      ]
    },
    {
      "name": "brush_tuple_fields",
      "value": [{"field": "month_date", "channel": "x", "type": "E"}]
    },
    {
      "name": "brush_translate_anchor",
      "value": {},
      "on": [
        {
          "events": [
            {"source": "scope", "type": "mousedown", "markname": "brush_brush"}
          ],
          "update": "{x: x(unit), y: y(unit), extent_x: slice(brush_x)}"
        }
      ]
    },
    {
      "name": "brush_translate_delta",
      "value": {},
      "on": [
        {
          "events": [
            {
              "source": "window",
              "type": "mousemove",
              "consume": true,
              "between": [
                {
                  "source": "scope",
                  "type": "mousedown",
                  "markname": "brush_brush"
                },
                {"source": "window", "type": "mouseup"}
              ]
            }
          ],
          "update": "{x: brush_translate_anchor.x - x(unit), y: brush_translate_anchor.y - y(unit)}"
        }
      ]
    },
    {
      "name": "brush_zoom_anchor",
      "on": [
        {
          "events": [
            {
              "source": "scope",
              "type": "wheel",
              "consume": true,
              "markname": "brush_brush"
            }
          ],
          "update": "{x: x(unit), y: y(unit)}"
        }
      ]
    },
    {
      "name": "brush_zoom_delta",
      "on": [
        {
          "events": [
            {
              "source": "scope",
              "type": "wheel",
              "consume": true,
              "markname": "brush_brush"
            }
          ],
          "force": true,
          "update": "pow(1.001, event.deltaY * pow(16, event.deltaMode))"
        }
      ]
    },
    {
      "name": "brush_modify",
      "on": [
        {
          "events": {"signal": "brush_tuple"},
          "update": "modify(\"brush_store\", brush_tuple, true)"
        }
      ]
    }
  ],
  "marks": [
    {
      "name": "brush_brush_bg",
      "type": "rect",
      "clip": true,
      "encode": {
        "enter": {"fill": {"value": "#333"}, "fillOpacity": {"value": 0.125}},
        "update": {
          "x": [
            {
              "test": "data(\"brush_store\").length && data(\"brush_store\")[0].unit === \"layer_0\"",
              "signal": "brush_x[0]"
            },
            {"value": 0}
          ],
          "y": [
            {
              "test": "data(\"brush_store\").length && data(\"brush_store\")[0].unit === \"layer_0\"",
              "value": 0
            },
            {"value": 0}
          ],
          "x2": [
            {
              "test": "data(\"brush_store\").length && data(\"brush_store\")[0].unit === \"layer_0\"",
              "signal": "brush_x[1]"
            },
            {"value": 0}
          ],
          "y2": [
            {
              "test": "data(\"brush_store\").length && data(\"brush_store\")[0].unit === \"layer_0\"",
              "field": {"group": "height"}
            },
            {"value": 0}
          ]
        }
      }
    },
    {
      "name": "layer_0_marks",
      "type": "rect",
      "style": ["bar"],
      "interactive": true,
      "from": {"data": "data_1"},
      "encode": {
        "update": {
          "fill": {"value": "#4c78a8"},
          "opacity": [
            {
              "test": "!length(data(\"brush_store\")) || vlSelectionTest(\"brush_store\", datum)",
              "value": 1
            },
            {"value": 0.7}
          ],
          "ariaRoleDescription": {"value": "bar"},
          "description": {
            "signal": "\"date (month): \" + (timeFormat(datum[\"month_date\"], timeUnitSpecifier([\"month\"], {\"year-month\":\"%b %Y \",\"year-month-date\":\"%b %d, %Y \"}))) + \"; Mean of precipitation: \" + (format(datum[\"mean_precipitation\"], \"\"))"
          },
          "x": {"scale": "x", "field": "month_date"},
          "width": {"scale": "x", "band": 1},
          "y": {"scale": "y", "field": "mean_precipitation"},
          "y2": {"scale": "y", "value": 0}
        }
      }
    },
    {
      "name": "layer_1_marks",
      "type": "rule",
      "style": ["rule"],
      "interactive": false,
      "from": {"data": "data_0"},
      "encode": {
        "update": {
          "stroke": {"value": "firebrick"},
          "description": {
            "signal": "\"Mean of precipitation: \" + (format(datum[\"mean_precipitation\"], \"\"))"
          },
          "x": {"field": {"group": "width"}},
          "x2": {"value": 0},
          "y": {"scale": "y", "field": "mean_precipitation"},
          "strokeWidth": {"value": 3}
        }
      }
    },
    {
      "name": "brush_brush",
      "type": "rect",
      "clip": true,
      "encode": {
        "enter": {"fill": {"value": "transparent"}},
        "update": {
          "x": [
            {
              "test": "data(\"brush_store\").length && data(\"brush_store\")[0].unit === \"layer_0\"",
              "signal": "brush_x[0]"
            },
            {"value": 0}
          ],
          "y": [
            {
              "test": "data(\"brush_store\").length && data(\"brush_store\")[0].unit === \"layer_0\"",
              "value": 0
            },
            {"value": 0}
          ],
          "x2": [
            {
              "test": "data(\"brush_store\").length && data(\"brush_store\")[0].unit === \"layer_0\"",
              "signal": "brush_x[1]"
            },
            {"value": 0}
          ],
          "y2": [
            {
              "test": "data(\"brush_store\").length && data(\"brush_store\")[0].unit === \"layer_0\"",
              "field": {"group": "height"}
            },
            {"value": 0}
          ],
          "stroke": [
            {"test": "brush_x[0] !== brush_x[1]", "value": "white"},
            {"value": null}
          ]
        }
      }
    }
  ],
  "scales": [
    {
      "name": "x",
      "type": "band",
      "domain": {"data": "data_1", "field": "month_date", "sort": true},
      "range": {"step": {"signal": "x_step"}},
      "paddingInner": 0.1,
      "paddingOuter": 0.05
    },
    {
      "name": "y",
      "type": "linear",
      "domain": {
        "fields": [
          {"data": "data_1", "field": "mean_precipitation"},
          {"data": "data_0", "field": "mean_precipitation"}
        ]
      },
      "range": [{"signal": "height"}, 0],
      "nice": true,
      "zero": true
    }
  ],
  "axes": [
    {
      "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": "date (month)",
      "format": {
        "signal": "timeUnitSpecifier([\"month\"], {\"year-month\":\"%b %Y \",\"year-month-date\":\"%b %d, %Y \"})"
      },
      "formatType": "time",
      "labelOverlap": true,
      "zindex": 0
    },
    {
      "scale": "y",
      "orient": "left",
      "grid": false,
      "title": "Mean of precipitation",
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "zindex": 0
    }
  ]
}