interactive_bar_select_highlight.vg.json

{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "description": "A bar chart with highlighting on hover and selecting on click. (Inspired by Tableau's interaction style.)",
  "background": "white",
  "padding": 5,
  "height": 200,
  "style": "cell",
  "data": [
    {
      "name": "highlight_store",
      "transform": [{"type": "collect", "sort": {"field": "_vgsid_"}}]
    },
    {
      "name": "select_store",
      "transform": [{"type": "collect", "sort": {"field": "_vgsid_"}}]
    },
    {
      "name": "source_0",
      "values": [
        {"a": "A", "b": 28},
        {"a": "B", "b": 55},
        {"a": "C", "b": 43},
        {"a": "D", "b": 91},
        {"a": "E", "b": 81},
        {"a": "F", "b": 53},
        {"a": "G", "b": 19},
        {"a": "H", "b": 87},
        {"a": "I", "b": 52}
      ]
    },
    {
      "name": "data_0",
      "source": "source_0",
      "transform": [
        {"type": "identifier", "as": "_vgsid_"},
        {
          "type": "stack",
          "groupby": ["a"],
          "field": "b",
          "sort": {"field": [], "order": []},
          "as": ["b_start", "b_end"],
          "offset": "zero"
        },
        {
          "type": "filter",
          "expr": "isValid(datum[\"b\"]) && isFinite(+datum[\"b\"])"
        }
      ]
    }
  ],
  "signals": [
    {"name": "x_step", "value": 20},
    {
      "name": "width",
      "update": "bandspace(domain('x').length, 0.2, 0.1) * x_step"
    },
    {
      "name": "unit",
      "value": {},
      "on": [
        {"events": "mousemove", "update": "isTuple(group()) ? group() : unit"}
      ]
    },
    {
      "name": "highlight",
      "update": "vlSelectionResolve(\"highlight_store\", \"union\", true, true)"
    },
    {
      "name": "select",
      "update": "vlSelectionResolve(\"select_store\", \"union\", true, true)"
    },
    {
      "name": "highlight_tuple",
      "on": [
        {
          "events": [{"source": "scope", "type": "mouseover"}],
          "update": "datum && item().mark.marktype !== 'group' ? {unit: \"\", _vgsid_: (item().isVoronoi ? datum.datum : datum)[\"_vgsid_\"]} : null",
          "force": true
        },
        {"events": [{"source": "view", "type": "dblclick"}], "update": "null"}
      ]
    },
    {
      "name": "highlight_toggle",
      "value": false,
      "on": [
        {
          "events": [{"source": "scope", "type": "mouseover"}],
          "update": "event.shiftKey"
        },
        {"events": [{"source": "view", "type": "dblclick"}], "update": "false"}
      ]
    },
    {
      "name": "highlight_modify",
      "on": [
        {
          "events": {"signal": "highlight_tuple"},
          "update": "modify(\"highlight_store\", highlight_toggle ? null : highlight_tuple, highlight_toggle ? null : true, highlight_toggle ? highlight_tuple : null)"
        }
      ]
    },
    {
      "name": "select_tuple",
      "on": [
        {
          "events": [{"source": "scope", "type": "click"}],
          "update": "datum && item().mark.marktype !== 'group' ? {unit: \"\", _vgsid_: (item().isVoronoi ? datum.datum : datum)[\"_vgsid_\"]} : null",
          "force": true
        },
        {"events": [{"source": "view", "type": "dblclick"}], "update": "null"}
      ]
    },
    {
      "name": "select_toggle",
      "value": false,
      "on": [
        {
          "events": [{"source": "scope", "type": "click"}],
          "update": "event.shiftKey"
        },
        {"events": [{"source": "view", "type": "dblclick"}], "update": "false"}
      ]
    },
    {
      "name": "select_modify",
      "on": [
        {
          "events": {"signal": "select_tuple"},
          "update": "modify(\"select_store\", select_toggle ? null : select_tuple, select_toggle ? null : true, select_toggle ? select_tuple : null)"
        }
      ]
    }
  ],
  "marks": [
    {
      "name": "marks",
      "type": "rect",
      "style": ["bar"],
      "interactive": true,
      "from": {"data": "data_0"},
      "encode": {
        "update": {
          "fill": {"value": "#4C78A8"},
          "stroke": {"value": "black"},
          "cursor": {"value": "pointer"},
          "fillOpacity": [
            {
              "test": "!length(data(\"select_store\")) || vlSelectionIdTest(\"select_store\", datum)",
              "value": 1
            },
            {"value": 0.3}
          ],
          "strokeWidth": [
            {
              "test": "length(data(\"select_store\")) && vlSelectionIdTest(\"select_store\", datum)",
              "value": 2
            },
            {
              "test": "length(data(\"highlight_store\")) && vlSelectionIdTest(\"highlight_store\", datum)",
              "value": 1
            },
            {"value": 0}
          ],
          "ariaRoleDescription": {"value": "bar"},
          "description": {
            "signal": "\"a: \" + (isValid(datum[\"a\"]) ? datum[\"a\"] : \"\"+datum[\"a\"]) + \"; b: \" + (format(datum[\"b\"], \"\"))"
          },
          "x": {"scale": "x", "field": "a"},
          "width": {"scale": "x", "band": 1},
          "y": {"scale": "y", "field": "b_end"},
          "y2": {"scale": "y", "field": "b_start"}
        }
      }
    }
  ],
  "scales": [
    {
      "name": "x",
      "type": "band",
      "domain": {"data": "data_0", "field": "a", "sort": true},
      "range": {"step": {"signal": "x_step"}},
      "paddingInner": 0.2,
      "paddingOuter": 0.1
    },
    {
      "name": "y",
      "type": "linear",
      "domain": {"data": "data_0", "fields": ["b_start", "b_end"]},
      "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": "a",
      "labelAlign": "right",
      "labelAngle": 270,
      "labelBaseline": "middle",
      "zindex": 0
    },
    {
      "scale": "y",
      "orient": "left",
      "grid": false,
      "title": "b",
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "zindex": 0
    }
  ]
}