Calculating the vector averaged direction requires a vector, so the
observation type is 'wind', which is a vector, not 'windDir'. The
aggregation that returns direction from a vector is 'vecdir', so, you want:
(start_ts, stop_ts, dirs) = weewx.xtypes.get_series('wind', x_domain,
db_lookup(data_binding=binding), 'vecdir', aggregate_interval)
Unfortunately, 'wind' appears only in the daily summaries. This means
aggregate_interval must be multiples of one day. This restriction could be
relaxed should someone want to write the necessary xtypes extension.
On Sun, Oct 16, 2022 at 6:35 AM James Taylor <
[email protected]> wrote:
> Hello
>
> Following on from https://github.com/weewx/weewx/issues/798, I've been
> trying to replicate and understand weewx behaviour when it comes to using
> get_series and get_aggregate.
>
> So if you are trying to aggregate winddir for graphing purposes, you want
> to get a wind vector which I understand
>
> Here is my example where my data is being archived every 300 seconds
>
> (time_start_vt, time_stop_vt, obs_vt) = weewx.xtypes.get_series(
> obs_lookup, x_domain, db_lookup(data_binding=binding), aggregate_type,
> aggregate_interval)
>
> obs_lookup is windDir
> Start time is 1665440100 and end time is 1665442800
> x_domain entries are 1665440100 and 1665442800
> aggregate_type is avg
> aggregate_interval is 300
> ([355.0, 355.0, 355.0, 355.480837630687, 0.0, 0.0, 0.0, 0.0,
> 4.249651034454402], 'degree_compass', 'group_direction')
> aggregate_interval is 900
> ([355.0, 118.49361254356234, 1.416550344818134], 'degree_compass',
> 'group_direction')
>
> I can see for the second group it is returning an average rather than a
> vector value of around 358.5, but trying to understand how we should be
> coding it.
>
> If I can change to aggregate of vecdir or vecavg I get a UnknownType error
>
> Any help will be appreciated here.
>
> James
>
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