No Vega ou Vega Lite, quero criar um gráfico de áreas empilhadas onde posso alterar o campo usado para colorir a visualização. Aqui está um exemplo de visualização . Neste exemplo, gostaria de poder alternar entre o agrupamento por "Cilindros", "Potência" e "Aceleração". Esta é uma versão simplificada do que estou tentando fazer, mas ilustra bem o ponto. Tentei definir o campo como um sinal anexado a um menu suspenso, mas isso não parece funcionar:
"fill": {
"scale": "color_by_cylinders",
"field": {"signal": "Group_By"}
},
Mesmo que funcionasse, eu ainda precisaria alterar a escala de cores com base no menu suspenso. Também precisaria alterar o campo pelo qual agregamos. Existe alguma maneira de fazer isso no Vega ou no Vega Lite?
{
"$schema": "https://vega.github.io/schema/vega/v6.json",
"autosize": {"type": "fit-x", "contains": "padding"},
"background": "white",
"padding": 5,
"height": 250,
"style": "cell",
"data": [
{"name": "Group_By_store"},
{
"name": "source_0",
"url": "data/cars.json",
"format": {"type": "json"},
"transform": [
{
"type": "aggregate",
"groupby": ["Origin", "Cylinders"],
"ops": ["count"],
"fields": [null],
"as": ["__count"]
},
{
"type": "stack",
"groupby": ["Origin"],
"field": "__count",
"sort": {"field": ["Cylinders"], "order": ["descending"]},
"as": ["__count_start", "__count_end"],
"offset": "zero"
}
]
}
],
"signals": [
{
"name": "width",
"init": "isFinite(containerSize()[0]) ? containerSize()[0] : 300",
"on": [
{
"update": "isFinite(containerSize()[0]) ? containerSize()[0] : 300",
"events": "window:resize"
}
]
},
{
"name": "unit",
"value": {},
"on": [
{"events": "pointermove", "update": "isTuple(group()) ? group() : unit"}
]
},
{
"name": "Group_By",
"value": null,
"bind": {
"input": "select",
"options": ["Cylinders", "Horsepower", "Acceleration"],
"labels": ["Cylinders", "Horsepower", "Acceleration"]
}
}
],
"marks": [
{
"name": "marks",
"type": "rect",
"style": ["bar"],
"interactive": true,
"from": {"data": "source_0"},
"encode": {
"update": {
"fill": {
"scale": "color_by_cylinders",
"field": {"signal": "Group_By"}
},
"ariaRoleDescription": {"value": "bar"},
"description": {
"signal": "\"Origin: \" + (isValid(datum[\"Origin\"]) ? datum[\"Origin\"] : \"\"+datum[\"Origin\"]) + \"; Number of Cars: \" + (format(datum[\"__count\"], \"\")) + \"; Cylinders: \" + (isValid(datum[\"Cylinders\"]) ? datum[\"Cylinders\"] : \"\"+datum[\"Cylinders\"])"
},
"x": {"scale": "x", "field": "Origin"},
"width": {"signal": "max(0.25, bandwidth('x'))"},
"y": {"scale": "y", "field": "__count_end"},
"y2": {"scale": "y", "field": "__count_start"}
}
}
}
],
"scales": [
{
"name": "x",
"type": "band",
"domain": {"data": "source_0", "field": "Origin", "sort": true},
"range": [0, {"signal": "width"}],
"paddingInner": 0.1,
"paddingOuter": 0.05
},
{
"name": "y",
"type": "linear",
"domain": {
"data": "source_0",
"fields": ["__count_start", "__count_end"]
},
"range": [{"signal": "height"}, 0],
"nice": true,
"zero": true
},
{
"name": "color_by_horsepower",
"type": "ordinal",
"domain": {"data": "source_0", "field": "Cylinders", "sort": true},
"range": "category"
},
{
"name": "color_by_acceleration",
"type": "ordinal",
"domain": {"data": "source_0", "field": "Cylinders", "sort": true},
"range": "category"
},
{
"name": "color_by_cylinders",
"type": "ordinal",
"domain": {"data": "source_0", "field": "Cylinders", "sort": true},
"range": "category"
}
],
"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": "Origin",
"labelAlign": "right",
"labelAngle": 270,
"labelBaseline": "middle",
"zindex": 0
},
{
"scale": "y",
"orient": "left",
"grid": false,
"title": "Number of Cars",
"labelOverlap": true,
"tickCount": {"signal": "ceil(height/40)"},
"zindex": 0
}
],
"legends": [
{"fill": "color_by_cylinders", "symbolType": "square", "title": "Cylinders"}
],
"config": {}
}