Delta between two set of data

[notarolap]

Hi everybody!

I'm having some issues calculating the deltas for a set of data.

Each day I get an extraction with the timestamp of that day. I need to show in a graph difference between one day and the day before.

For the table below I should get the delta 20-40=-20

I would like to show this -20  (and all daily deltas) in a graph, I tried the formula 
aggr(sum([Order Quantity]),[Data Ext.])-aggr(sum([Order Quantity]),[Data Ext.]-1)
but is not working.

Data	Qty
05/05/2021	10
05/05/2021	10
05/05/2021	10
05/05/2021	10
06/05/2021	5
06/05/2021	5
06/05/2021	5
06/05/2021	5

thanks a lot!
Nicolas

[OmarBenSalem · Accepted solution]

Try aggr( sum(Qty)- above(sum(Qty)),Data)

[notarolap]

Thanks a lot!! 

[notarolap]

Hi Omar,

Thanks again for your help!

I have a couple of question:

- How can I agrupate by year-week? I created a new field (Year_Week) but when I use the formula below I'm not getting the correct numbers:

aggr(sum([Order Quantity])-above(sum([Order Quantity])),Year_Week)

- How can I manage this first value (where you dont have an "Above" to subtract)?

Thanks!

[OmarBenSalem]

what qlik version are you using? because in the newest version, qlik proposes do calculate this for you !

create your measure and then :

As for the first value, it's normal to not have it since there is no value above, right?