Calculation in vega - vega

Question

I use vega in Kibana.
I select two values from two different index in section "data". But now I need to summarize this values and visualize it in the section "marks". Is anybody know, how can I do this? Now in the section "marks" I use only one value from first "data".
My code is the following:
{
"$schema": "https://vega.github.io/schema/vega/v3.0.json",
"title": {
"text": "Lead time, hr.",
"orient": "bottom"
},
"data": [
{
"name": "source_1",
"url": {
"index": "metrics-bitbucket-*",
"%context_query%": "#timestamp",
"body": {
"size": 0,
"aggs": {
"etb": {
"avg": {
"field": "elapsed_time",
"script": {"source": "_value/3600*10"}
}
}
}
}
},
"format": {"type": "json", "property": "aggregations.etb"}
},
{
"name": "source_2",
"url": {
"index": "metrics-jenkins-*",
"%context_query%": "#timestamp",
"body": {
"size": 0,
"aggs": {
"etj": {
"avg": {
"field": "elapsed_time",
"script": {"source": "_value/3600*10"}
}
}
}
}
},
"format": {"type": "json", "property": "aggregations.etj"}
}
],
"marks": {
"type": "text",
"from": {"data": "source_1"},
"encode": {
"update": {
"text": {"signal": "round(datum.value)/10"},
"fontSize": {"value": 60},
"fontStyle": {"value": "bold"},
"x": {"signal": "width/2-50"},
"y": {"signal": "height/2"}
}
}
}
}

Answer 1

You essentially have two lists of data objects: source1: [{}, {}, ...] and source2: [{}, {}, {}, ...]. When you draw items, you have to specify just one data source. That data source could be the concatenation of the first two, e.g. you create source3 with its source parameter set to ["source1", "source2"], which includes all elements from both, but I suspect this is not what you want here. Rather, you need to merge the data using lookup transform - iterate over the items in one data source, and pull the corresponding values from another data source. Afterwards, add a formula transform to sum the values. The mark would than use the result of the formula for drawing.