How do I use aggregates in grouped marks? - powerbi

Question

I'm trying to use the min and max aggregates of a quantitative column (Total bombers) grouped by another column (Country) in a rule mark of my visual. I want the rule y property to start at the minimum value of Total bombers and the rule y2 property to end at the maximum value of total bombers, but I can't seem to find the right syntax for the min and max aggregates of the rule mark. I can get the result I'm looking for by not grouping the marks but I would like to implement it for grouped marks so I can re-use it more easily.
Spec for grouped version I'm trying to use min and max aggregates in:
https://vega.github.io/editor/#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-dADW0Hux6npTFMgA
Spec for non-grouped version that achieves what I want to do:
https://vega.github.io/editor/#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-IKCpocGMshqAGFczNFIWZMRMgx5VSaXS+dlhSnvejlaqQOr0CbtfZdTUzRaptPNVaS06na7kyBcV70IrBx4R5TqZku2CWiAgxrQzkAOQAZTYxArtgAquJ1Be8toANTaecIS9PuhwWRtCvEopggV9BTyXsQEqeU4FIGZjxbYw20ZcoQAAOSceUhxLNB7SeSIZAAEQUKBlFUdQagAGRWRBtBUCAWVXTCqhqJgOQjPDdgANmCEASKUFQ1AkGoAEk8BZExaOlAUy1FJBxUVGU1zlfspW3NVGRDLVAwnYM52KU0aCNb9w1tB1lzdWTZNSKBMgUZSYJqewPHXeUzQ8MUyHlbxfBgDxZHqJAzHJTVSlqelmlRCsqzPLUhQ9aCsJqJsVI3EBTHMbkZC8+VQnCTNoMMAlRTbGQAC8mjYNBSrgQogpC1BQDCtjIuPH1K2rdAOwPOpu0FKCnMJNhjBWVzVPQFZEgyDocoU7yajsqYyBWVLAuQRrmuKcK+qPaLOtretRULIUyyQewHLKUAVgrGZWuweoPGgeznNXG7pkxdBXA+QrntcFKIJkZBFAAa1Q5rSPI4SNBAKizAsSU7CWZDoe0NgPm0B8r0PBlxvSzLqhkD4c2lJrtJ2tr3RPcQJnkckPrZMmXLJv75RcomYq67TqmFEBCxZuz-vQVKOti9A-ymQDgMMntUlFNgQbgGt4XJJC2xqHMGHEatef6HNFYAdR8PwybVgktl1+XFYAeTiKA6H50AzbQAJKAEIUEohwSKJE9AAAU2DMTAIG0RGsZxqKRQmkAIBxBoRtREnQu21r+t56ZaYJUAGb1UBmdAVnXo5g7R0MqnHZjwX5RFzmaglgCgJAhzdZoSrVdbAlAl5n1jA6AWXuG0aA3LEuQDrLXjqpvWFbgI2-Pb5CCWiS39azkBna+sIsAgEGcSYReBtaHAxzJnvjFtpB7dxBf1dQe0V5ni+r4rjeAgSjBb0ZgurbgJ+HZvgk98PaJXkN7aG1F4ahxWEjEaDBUboyAree8EdjxuRqATROj0yYtXQLtXG6caZsDpmTHO5J86VwHiAdmI8xbc3LuSQuwt9q0JvHeU0mNnwiQforZWOAAEa3rDrOWq854mydh3NAFthGPztv-U2EjUCu3dsAr2ZEhKUX9oHBCUDIysOQXgyOaV5Sx3jrNBUSdsEp1wZTAhmd6YzC-lQhhVci40K5mOXmFdGF82YVzPR7C-xcNSK3NeG8u4c17s4yhEwh6+MOhPRsU8f6iP8vIg+qBl7SMVvwzeBUd57wPu-PMJ9QBnz-tfNJt975ZN-rIip4j0lv15jAT+ucY4-3KS-BRQDPZGI1sqQm5isFbRKKnPatiiFr1IUzKJQsnHF1oR4mQXiXFMIWX4pBATOGSE8ZEWZ1c4ni2fJLRuMsp4hJyeE8skT+5zJiWNdZ8SGwnRqSky53DQkKIylvYOu997qyKcfMup9fTnzqV09J1T2mr06Tk12FtmmtIYR08FOSenWSAA
Any help much appreciated!

Answer 1

What you're trying to do isn't logically possible. You have faceted on country. That means each country gets a line (working), a symbol (working) but how would it get a rule where the start point is one country and the end point is the other. One group does not know anything about the other group so you couldn't have a rule spanning the two countries.
If you want to keep your facet, you can do the following:
{
"$schema": "https://vega.github.io/schema/vega/v5.json",
"description": "A basic line chart example.",
"width": 500,
"height": 200,
"padding": 5,
"signals": [],
"data": [
{
"name": "bombers",
"url": "https://gist.githubusercontent.com/vdvoorder/5b30997d8708dda783bb2b95d2e9ef34/raw/Bomber%2520Gap.csv",
"format": {
"type": "csv",
"parse": {"Total bombers": "number", "Year": "number"}
},
"transform": [
{
"type": "formula",
"as": "date",
"expr": "time(datetime(datum.Year, 1, 1))"
},
{"type": "filter", "expr": "datum.Year <= 1980"}
]
},
{
"name": "bombers2",
"source": "bombers",
"transform": [
{
"type": "pivot",
"field": "Country",
"value": "Total bombers",
"groupby": ["date"]
}
]
}
],
"scales": [
{
"name": "x",
"type": "time",
"range": "width",
"domain": {"data": "bombers", "field": "date"}
},
{
"name": "y",
"type": "linear",
"range": "height",
"nice": true,
"zero": true,
"domain": {"data": "bombers", "field": "Total bombers"}
},
{
"name": "color",
"type": "ordinal",
"range": "category",
"domain": {"data": "bombers", "field": "Country"}
}
],
"axes": [
{"orient": "bottom", "scale": "x"},
{"orient": "left", "scale": "y"}
],
"marks": [
{
"type": "group",
"from": {
"facet": {"name": "series", "data": "bombers", "groupby": "Country"}
},
"marks": [
{
"description": "Line for evolution of total bombers by country",
"type": "line",
"from": {"data": "series"},
"encode": {
"enter": {
"x": {"scale": "x", "field": "date"},
"y": {"scale": "y", "field": "Total bombers"},
"stroke": {"scale": "color", "field": "Country"},
"strokeCap": {"value": "round"},
"strokeWidth": {"value": 3},
"strokeOpacity": {"value": 0.5}
}
}
},
{
"description": "Points for total bombers by country",
"type": "symbol",
"from": {"data": "series"},
"encode": {
"enter": {
"x": {"scale": "x", "field": "date"},
"y": {"scale": "y", "field": "Total bombers"},
"size": {"value": 50},
"fill": {"scale": "color", "field": "Country"},
"strokeWidth": {"value": 20},
"stroke": {"value": "lightskyblue"}
},
"update": {
"fillOpacity": {"value": 1},
"strokeOpacity": {"value": 0}
},
"hover": {"strokeOpacity": {"value": 1}}
}
}
]
},
{
"description": "Rulers between country total bomber numbers",
"type": "rule",
"from": {"data": "bombers2"},
"encode": {
"update": {
"x": {"scale": "x", "field": "date"},
"y": {"scale": "y", "field": "Soviet Union"},
"y2": {"scale": "y", "field": "United States"},
"stroke": {"value": "lightskyblue"},
"strokeWidth": {"value": 3},
"strokeOpacity": {"value": 0.5}
}
}
}
]
}