Recursive equation in repeating group

1theritzy · 2025-01-27T19:33:40.488Z

Hi Bubble team,

I am using a repeating group to generate data for a graph.

One of the important calculations in the RG is a recursive equation, that is, each row depends on the answer in the previous row. It’s really easy to do in an Excel spreadsheet, simple as (Row 2) (Collum 1) = (Row 1) (Collum 1) + 1.

How do you access an input in the previous row? I can do it using List Calculator but it’s very wonky. I hope there is a better way.

Thanks!

jonathan.baxter1991 · 2025-01-27T21:20:31.821Z

When are the entries created for the repeating group? Usually you would do it then. Otherwise maybe you could use current cells index within the repeating group assuming you want the first entry to always start with 1.

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1theritzy · 2025-01-27T21:40:14.118Z

The problem is I don’t know how to write the equation as “current cell (index - 1)” in an input.

I can only do it using the ListCalculator

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J805 · 2025-01-29T16:13:11.099Z

Hey @1theritzy

That’s a good question.

My suggestion, just save the value in the database. Don’t try to calculate it on the fly. Does that make sense?

Is the graph dynamic based on filters or something? In that case, there is another option too.

Let me know.

1theritzy · 2025-01-29T21:25:54.400Z

Yes, it uses dynamic data with user input. The problem is the financial equations build on the result of the previous row. The way I have it with the list calculator works mostly, just gives me some glitchiness I’m trying to solve.

Extremely easy to do in an excel spreadsheet.

J805 · 2025-01-29T22:50:24.574Z

Yeah, this sort of thing is very easy in excel for sure.

You might need to save the data source to something like a state first. Then access the data from there.