Charting item aggregate value or Sum by day

Setup, Configuration and Use Items & Sitemaps
1

Is it possible to chart by an aggregate value .
eg If I write hourly can I sum for a daily chart?

2

There are not a lot of details to go on here, but in general create a separate Item to store the daily sum. At midnight (or there about) trigger a rule to calculate the daily total and update the daily sum Item.

3

Clarification, I’m persisting a item every hour, however I’d like to chart by day but sum the values.
ie I’m logging kwh every hour and would like see daily totals over the month.

4

Same answer. If you want to chart by day, you gotta save the data by day in a different Item (or change your existing Item to only save once per day).

5

I don’t think it can be that simple unfortunately.
I was just thinking about a similar issue to count the number of lightning per N hours.
You cannot just reset a counter every N hours since the latest records may not be N hours old.
So in theory, you would need to store timestamp + occurence or count and regularly delete the records that are too old.

For those, I am wondering if the best option is not to:

  • use persistence to persist the events (lightning, whatever, …)
  • run a query to the persistance DB to get the values
6

That’s exactly what I’m sugesting be done.

The “calculate the daily total” part is going to be something like items.MyItem.persistence.sumSince(time.toZDT('P-1DT')); (JS Scripting).