How to count row combinations based on common value - powerbi

Question

I'm trying to find the frequency of combinations that occur per an ID value.
Example given here: https://i.stack.imgur.com/ZG9gJ.png
The problem is that the number of rows that could make up a combination is variable, meaning a combination could consist of just 1 value or 2, 3, 4, etc.
I'm currently trying to do this within Power BI, but perhaps another tool would be more appropriate.

Answer 1

You can do this with Power Query (from Power BI => Transform)
Basic algorithm
Group by ID
for each subGroup
Concatenate a sorted list of Cats
Count the number of Cats per ID for subsequent sorting
Then Group by COMBI
Aggregate with Count function
M Code
let
//change next line to however you are getting your table
Source = Excel.CurrentWorkbook(){[Name="idCat"]}[Content],
#"Changed Type" = Table.TransformColumnTypes(Source,{{"ID", Int64.Type}, {"Cat1", type text}}),
//group by ID and create COMBI
// and also length of each cat string for subsequen intelligent sorting
#"Grouped Rows" = Table.Group(#"Changed Type", {"ID"}, {
{"COMBI", each Text.Combine(List.Sort([Cat1])),type text},
{"lenCat", each Text.Length(Text.Combine(List.Sort([Cat1]))),Int64.Type}
}),
maxLen = List.Max(#"Grouped Rows"[lenCat]),
#"Delete length column" = Table.RemoveColumns(#"Grouped Rows","lenCat"),
//Group by Cats for counting
#"Grouped Cats" = Table.Group(#"Delete length column",{"COMBI"},{
{"COUNT", each List.Count([COMBI]), Int64.Type}
}),
#"Pad COMBI for Sorting" = Table.TransformColumns(#"Grouped Cats",{"COMBI", each Text.PadStart(_,maxLen), type text}),
#"Sorted Rows" = Table.Sort(#"Pad COMBI for Sorting",{{"COMBI", Order.Ascending}}),
#"Trim Leading Spaces" = Table.TransformColumns(#"Sorted Rows",{"COMBI", each Text.Trim(_), type text})
in
#"Trim Leading Spaces"