The idea is to "transform" the column based data into a parent, child structure in order to apply a Stratify transform.
Starting data:
{
"value": 140,
"level1": "France",
"level2": "Reins",
"level3": "Jean Monnet",
"level4": "rue 3 ",
"level5": "no",
"level6": "a level"
}
First group by all the levels or depth of the sunburst according to your value or quantity.
"transform": [
{
"type": "aggregate",
"groupby": [
"level1",
"level2",
"level3",
"level4",
"level5",
"level6"
],
"fields": [
"value"
],
"ops": [
"sum"
],
"as": [
"value"
]
}
]
Secondly, we need to have a root note for stratify, so based on available data we can transform our data as following to define our root node having level1 elements as child nodes:
{
"name": "isolatedLevel1",
"source": [
"mainData"
],
"transform": [
{
"type": "project",
"fields": [
"level1",
"currentNode",
"value"
],
"as": [
"currentNode",
"parent",
"value"
]
},
{
"type": "aggregate",
"groupby": [
"parent",
"currentNode"
],
"fields": [
"value"
],
"ops": [
"sum"
],
"as": [
"value"
]
},
{
"type": "formula",
"as": "parent",
"expr": "!isDefined(datum.parent)?'rootID':datum.parent"
},
{
"type": "project",
"fields": [
"currentNode",
"parent",
"value"
],
"as": [
"currentNode",
"parent",
"value"
]
},
{
"type": "filter",
"expr": "datum.currentNode"
}
]
},
{
"name": "rootNode",
"source": "isolatedLevel1",
"transform": [
{
"type": "project",
"fields": [
"parent",
"level2"
],
"as": [
"currentNode",
"parent"
]
},
{
"type": "aggregate",
"groupby": ["currentNode","parent"]
},
{
"type": "project",
"fields": [
"currentNode",
"parent"
],
"as": [
"currentNode",
"parent"
]
}
]
},
{
"name": "isolatedLevel1MergedWithParent",
"source": [
"isolatedLevel1",
"rootNode"
]
},
Then, the idea is to determine for the upcoming levels, the parent and child between 2 levels.
We can apply this data transform and repeat it till the last level of our data.
{
"name": "isolatedLevel2",
"source": "mainData",
"transform": [
{
"type": "project",
"fields": [
"level1",
"level2",
"value"
],
"as": [
"parent",
"currentNode",
"value"
]
},
{
"type": "aggregate",
"groupby": [
"parent",
"currentNode"
],
"fields": [
"value"
],
"ops": [
"sum"
],
"as": [
"value"
]
},
{
"type": "project",
"fields": [
"currentNode",
"parent",
"value"
],
"as": [
"currentNode",
"parent",
"value"
]
},
{
"type": "filter",
"expr": "datum.currentNode"
},
{
"type": "filter",
"expr": "datum.parent"
}
]
}
Finally, we merge all these "decomposed" transforms all together to get back our data, transformed into a parent child hierarchy, with values associated to its nodes only. This is a way to suit your data to a Stratify VEGA transform.
{
"name": "mergedlevelsFinal",
"source": [
"isolatedLevel1",
"isolatedLevel2",
"isolatedLevel3",
"isolatedLevel4",
"isolatedLevel5",
"isolatedLevel6",
"rootNode"
],
"transform": [
{
"type": "formula",
"as": "value",
"expr": "!indata('parents','parent',datum.currentNode)? datum.value:''"
}
]
}
The hard part gone, we can now apply our stratify to the transformed data as we want for our sunburst.
{
"name": "tree",
"source": [
"mergedlevelsFinal"
],
"transform": [
{
"type": "stratify",
"key": "currentNode",
"parentKey": "parent"
},
{
"type": "partition",
"field": "value",
"sort": {
"field": "value"
},
"size": [
{
"signal": "2 * PI"
},
{
"signal": "width / 3"
}
],
"as": [
"a0",
"r0",
"a1",
"r1",
"depth",
"children"
]
},
{
"type": "formula",
"expr": "!datum.children?datum.value:''",
"as": "value"
}
]
}
Full Spec Solution available here https://vega.github.io/editor/#/gist/0f66d06894b61f8ba131f13f564e8c1f/spec.json
