I need a Formula

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Posted on by SamuelParkes

I am trying to get a formula to suit the following situation:

- I have a data file with multiple columns of data.

- Essentially they get entered as categories say for example ice cream flavours.

- I have 3 entries for chocolate inventories, wednesday it was 15 litres, thrusday it was 20 litres.

- how do i get a formula to tell me what the difference is? i can use lookup to tell me what the first entry was but im having trouble with the negative value (what to take off that original value) in other words how to i look for the last value in a particular column?

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bean 568 on at

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If you could describe a bit better on how you want this to work, I might be able to write some code.

However, if you just want to work out the difference between two dates, you could simply just do two Lookups.. e.g.

UpdateContext({difference: Abs( LookUp(first value).litres-LookUp(second).litres ) })

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bean 568 on at

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In addition, to find the last row in a table, you can use Last() & LastN().

https://powerapps.microsoft.com/en-us/tutorials/function-first-last/

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SamuelParkes 23 on at

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Yeah i think this is the right way to go, however how to i use the filter with the first() and last() formulas?

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bean 568 on at

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Sorry - I may have set you in the wrong direction. I think, if you are using last() and first(), you would not use that with a filter.

So to simply get the last row, Last(datasource). To get a column value from last... I think you could try Last(datasource).columnname?

If you want the second to last row.. this is where things get a bit hacky. You would need to go First(LastN(datasource,2)).columnname

Hope that helps!

Sean

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SamuelParkes 23 on at

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Thanks heaps for your help. One more thing..
I got it to work the other day when i used the following formula:
first(filter(source,column name = dropdown.selected.value).column to return) then i did the same thing with last formula.
i did that and it worked but now im getting the following error:
"The property expects Text values, but this rule produces incompatible Record values."
Understanably its hard to understand where im at without knowing the sources/columns etc. But any help you can give would be greatly appreciated!!
Thanks so much

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