[Feature request] New aggregation: integral about iobroker.history

[Apollon77]

Data aggregation stuff is locate here: https://github.com/ioBroker/ioBroker.history/blob/master/lib/aggregate.js#L65 and "post pocessing" in https://github.com/ioBroker/ioBroker.history/blob/master/lib/aggregate.js#L117
For this all logic should be done as post-processing I think

[Apollon77]

Basic implementation maybe using https://www.npmjs.com/package/math-tools

[AlCalzone]

When integrating, that module seems to expect a function which has to be defined for all x-values (or time points) in the interval to integrate. We don't have that because we only have single data points. But we basically only need this simple formula:

// at the start of the interval:
integral = 0
// for each data point
integral += 0.5 * (current_value + prev_value) * (current_timestamp - prev_timestamp)

And the sum doesn't have to be recalculated each time if we somehow store the aggregated value. Then we only need to add the last part whenever a new data point arrives.

[Apollon77]

What Time.base we should use? h or min r sec or ms ? :-) Data-Timestamps has ms, so it would result in "Wms" :-)

[AlCalzone]

What Time.base we should use? h or min r sec or ms ? :-) Data-Timestamps has ms, so it would result in "Wms" :-)

As dumb as that sounds for energy consumption, I would use ms to have maximum flexibility. Maybe we can add a scaling factor, which would be 1/3600000 to turn Wms into Wh. Or make the time base configurable?

[Apollon77]

Please check out 2.0.0 https://forum.iobroker.net/topic/54197/test-adapter-history-2-0-0