Google Sheets Hierarchical Subcategory Expansion - google-sheets

Question

Problem Statement:
I have a list of bank transactions with an amount and a category.
I have categories defined as a string which can contain any number of : characters. The : character indicates a sub category. For example expenses Household contains all household expenses and Household : Utilities indicates the subcatogy Utiltities within houshold.
I can groupby the category and take the sum to get expenses within a specific subcategory. For example I can get the total spent on Household : Utilities or Household : Rent. But doing a groupby sum will not give me a Household entry which is the sum of the Utilities and Rent Subcategories.
I wish to be able to expand these sub category and parent category sums in in a Hierarchical way so that I have a comprehensive list. E.g If I have a transaction with Household : Utilties : Water for $10, and a transaction with Household : Utilities : Electricity for $15 I want the result to be
Household .............................. $ 25
Household : Utilities .................. $ 25
Household : Utilities : Water .......... $ 10
Household : Utilities : Electricity .... $ 15
This is a link to an example spreadsheet.
https://docs.google.com/spreadsheets/d/14URPJ4fWl6id9z0-AI1hxNClo-10gotKdMSXnuehNVI/edit?usp=sharing
I can get simple summary of category vs sum using a query() and groupby but this will not expand to parent categories.
I can do this in python, But am having difficulty getting my head around how I would do this in a spreadsheet. Does anyone have any ideas?

Answer 1

try:
=ARRAYFORMULA(QUERY({A5:B;
SPLIT(FLATTEN(IFERROR(REGEXREPLACE(REGEXREPLACE(IF(
IFERROR(SPLIT(A5:A, ":"))="",,A5:A),
IFERROR(SPLIT(A5:A, ":")), ), " :$| ::.+|^:.+", ))&"×"&B5:B), "×")},
"select Col1,sum(Col2)
where Col2 is not null
group by Col1
order by Col1
label Col1'Category',sum(Col2)'Quantity'"))