[vz-dev] line charts are wrong display style for "power" type data!

Jakob Hirsch jh at plonk.de
Tue Jun 28 16:54:31 CEST 2011


Harald Koenig, 2011-06-28 14:00:
> for "power" style data you must not draw lines between measurement
> points as this gives totally wrong graphs (esp. for pulse
> counters!).

Which version do you use?
We changes that a while ago to horizontal lines. Here's what it looks
like in the current version:

> so: for every measurement point you should draw some line or
> rectangle with the area beyond that line/rect being propotional to
> the energy in that time interval (== power_value * delta_time). thus

Well, the energy is always the same for a given sensor, e.g. for sensors
with 2000 impulses/kWh it's 0.5Wh/impulse, but I think you already knew
that :)
We measure the time between two impulses and therefore get the average
power in the time interval between the two impulses, which is the height
of the line.

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