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How do you find duplicates in a list?
This question has been posted here before, and tons of suggestions have been made, but no real solution has yet to be implemented that's practical and functional.
"Why is this so hard?" you ask???
Because many years ago, a decision was made about the following:
- When you subtract {list} - {list}, we're going to automatically apply UNQIUE() around the whole thing - removing any duplicates from that list.
But why would they do this? Why would they automatically put in a formula, around the formula I'm making?
That's a good question, and one I asked many years ago when this first came up; the answer I got was something akin to, "we're trying to help and make it easy for non-technical types."
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So I pose the question again... How do you find duplicates in a list?
Any method that you may try (other than some completely impractical unwieldy formulas) will reduce your resultant list to it's simplest terms - the very thing you're not trying to do.
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Proposed Solution
- Remove the automatic (list - list) reduction
- Communicate that Unique() can be used to simplify your lists if needed
- Build a system to go through every AppSheet app in operation (both deployed and prototypes), detect a (list - list) situation, and wrap them with the Unique() function.
- This will solve the problem the team communicated, of "not wanting to mess with current apps"
- Any apps currently built, that rely on this automatic reduction, will simply update to now include the UNIQUE() function around their list subtraction... and the resulting behavior of the app will continue along as people are expecting.
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But.... if you remove this automatic reduction to simplest terms, then the following would work:
LIST(1, 2, 3, 3,4) - LIST(1, 2, 3, 4) = LIST(3)
Thus allowing me to find the duplicate.
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Please and thank you... this has been a long time coming, and certain advanced calculations and functionalities won't work unless we can find duplicates.
