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kibanavega-litevega

Dynamic Chart Title From Data Values

I want to take the title of my vega-chart directly from the data which are base of the chart. For example the title of this chart should be 'charttitle':

{
"$schema": "https://vega.github.io/schema/vega-lite/v5.json",
"data": {
"values": [
{"quater":"1", "sales":"100", "title":"charttitle"},
{"quater":"2", "sales":"200", "title":"charttitle"},
{"quater":"3", "sales":"300", "title":"charttitle"},
{"quater":"4", "sales":"400", "title":"charttitle"}
]
},

"mark": "bar",
"encoding": {
"x": {"field": "quater", "type":"ordinal"},
"y": {"field": "sales", "type": "quantitative"},
},
"title": ???
}

In pseudo code it could look like this:

"title": (select title from data limit 1); or in standard sql

"title": (select top 1 title from data)

but how can i achieve that in vega?

Solution

  • enter image description here

    {
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {
    "values": [
      {"quater": "1", "sales": "100", "title": "charttitle"},
      {"quater": "2", "sales": "200", "title": "charttitle"},
      {"quater": "3", "sales": "300", "title": "charttitle"},
      {"quater": "4", "sales": "400", "title": "charttitle"}
    ]
  },
  "mark": "bar",
  "encoding": {
    "x": {"field": "quater", "type": "ordinal"},
    "y": {"field": "sales", "type": "quantitative"}
  },
  "title": {"text": {"expr": "data('source_0')[0].title"}}
}