CODEWITHSUNDEEP
monitoringgrafanametricsinfluxdb
Daniel F
Daniel F

Reputation: 14239

Offsetting a graph by the first value of the shown time span

I have a graph of an energy meter in Grafana which shows the value of the consumed active energy over the selected time span.

enter image description here

This is a relatively new meter, a few months old, so the highest value it is currently showing is around 1570.3 kWh.

The interval shown in the image above is over the course of 24h, so it starts at 1568.1 kWh.

I want to offset the entire graph by 1568.1 kWh, so that the beginning of the graph is at 0 kWh and the end at 2200 Wh (~ 91 Wh per hour in average over 24 h).

It should always adjust when I change the selected time span, so that I can get a good overview of the daily, weekly or monthly consumption.

How do I archive this?

I read that using something like SELECT integral(derivative(max("in-value"))) ... would do the job, but I didn't get it to work. Also, I believe that just adding a SELECT max("in-value") - first_value_of_timespan("in-value") ... would be more precise and efficient, but such a method first_value_of_timespan does not exist.

Upvotes: 0

Views: 594

Answers (1)

Daniel F
Daniel F

Reputation: 14239

The solution is to take the difference between the current interval and the next one (there are many small intervals in the shown time span), and then to do a cumulative_sum over all the differences of the time range.

In the specific case shown in the question the solution would be

SELECT cumulative_sum(difference(max("in-total"))) FROM "le.e6.haus.strom.zähler.hausstrom-solar" WHERE $timeFilter GROUP BY time($__interval) fill(previous)

Upvotes: 2

Related Questions