Group and sum interval values per day

[AidanByrne]

Hi,
I have a months worth of electrical meter values at 15 min kWh meter values. I would like to calculate the interval value by subtracting a value from the preceding value then sum the interval values for any given day.
At the end of the workflow I want Date and total kWh for that day.
Can you please give me some advice on how I achieve this in knime?
Thanks for your help.

[andrejz]

Hi,

I will start with Lag column node so you can easily calculate the difference with Math formula node from the preceding value an continue by extracting the day (and month) from the DateTime column and in the end sum the differences with Group by node.

[AidanByrne]

Thank you Andrejz. That worked! .