Vegalite Keep Most Recent Data (Filter Transform) - vega-lite

Question

I have the following dashboard:
{
"$schema": "https://vega.github.io/schema/vega-lite/v5.json",
"description": "Domain Breakout Breakout",
"width": "container",
"title": {
"text": ["Build number by service name"],
"align": "center",
"dy": -10,
"fontWeight": "bold",
"color": "#4f597a",
"fontSize": 13,
"font": "Montserrat,sans-serif"
},
"config": {"axis": {"grid": true, "tickBand": "extent"}},
"data": {
"values": [
{
"service": "service1",
"build": 5555,
"env": "dev"
},
{
"service": "service2",
"build": 5555,
"env": "test"
},
{
"service": "service3",
"build": 5555,
"env": "staging"
},
{
"service": "service4",
"build": 5555,
"env": "prod"
},
{
"service": "service4",
"build": 5225,
"env": "prod"
}
]
},
"transform": [
{"pivot": "env", "value": "build", "groupby": ["env", "service","build"]}
],
"mark": "text",
"encoding": {
"x": {
"field": "env",
"type": "ordinal",
"sort": "descending",
"axis": {
"title": null,
"labelAngle": 0,
"labelFontWeight": "bold",
"labelColor": "#4f597a",
"labelFontSize": 20,
"labelPadding": 20,
"orient": "top"
}
},
"y": {
"field": "service",
"type": "ordinal",
"sort": {"field": "service", "order": "descending", "op": "sum"},
"axis": {
"title": null,
"labelAngle": 0,
"labelFontWeight": "bold",
"labelColor": "#4f597a",
"labelFontSize": 10,
"labelPadding": 5
}
}
},
"layer": [
{
"mark": "rect",
"width": 1000,
"encoding": {
"fill": {
"legend": null,
"field": "build",
"type": "quantitative",
"scale": {"range": ["#ecf9ff", "#c6efff", "#7ad9ff", "#42caff"]}
}
}
},
{
"mark": {
"type": "text",
"fontSize": 8,
"font": "Montserrat,sans-serif",
"align": "center"
},
"encoding": {"text": {"field": "build"}}
}
]
}
I have a use case in which new data is inserted with the same service name and env name but with a different build number. In this case:
{
"service": "service4",
"build": 5555,
"env": "prod"
},
{
"service": "service4",
"build": 5558,
"env": "prod"
}
The issue is the cell [service4][prod] has to layer the "old" value and the new value.
Is there an option in vega to get the last inseted value or something similar?
Link the dash: Link

Answer 1

You can use a combination of joinaggregate and filter transform to get the max of build number. i.e. it will filter out the lower values. e.g.
{
"joinaggregate": [{"op": "max", "field": "build", "as": "MaxBuild"}],
"groupby": ["service"]
},
{
"filter":"datum.build >= datum.MaxBuild"
}
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