Hi,
If I am understanding you correctly you have a field that is being
populated in the WeeWX database. The field data is such that you display
cumulative values or sums (ala rain) rather than point in time values (like
temperature, pressure etc). You have been scaling that field on your web
page. You would now like to plot that field but you wish to plot the scaled
data rather than the data stored in the field.
The WeeWX plot engine is fairly limited in abilities and essentially any
observation you want to plot needs to be stored in your archive. One
approach you could take is to use the StdCalibrate service to do your
scaling for you and provided the field containing the scaled value is
stored in the archive you can just plot the scaled value. For example, say
your data is coming from the console in field new_obs, something like:
[StdCalibrate]
[[Corrections]]
new_obs = new_obs * 36 if new_obs is not None else None
would result in your field new_obs now containing your scaled data and
provided new_obs is in the db schema it will be saved to archive and able
to be plotted. An alternative if you want to keep the original data in
new_obs would be to place the scaled data in a new field:
[StdCalibrate]
[[Corrections]]
another_obs = new_obs * 36 if new_obs is not None else None
This will result in your original sensor data remaining in field new_obs
and the scaled data being in field another_obs. Provided another_obs is in
your schema it will be saved to archive and able to be plotted. This data
will be in seconds and I suspect there will be some scaling issues on your
plots. You could alter the scaling formula to store your scaled data in
decimal hours and that may plot better, something like:
[StdCalibrate]
[[Corrections]]
another_obs = new_obs * 36/3600 if new_obs is not None else None
Rather than re-using existing database fields it is quite straightforward
to add new fields to the database. You can find information on adding new
fields to the database in the section Adding a new type to the database
<http://weewx.com/docs/customizing.htm#add_archive_type> in the
Customization Guide.
Hope that helps and I have not misunderstood your question.
Gary
On Sunday, 26 July 2020 02:39:58 UTC+10, Phil Owers wrote:
>
> Hi All
>
> Have been using the Instromet Stand Alone Sun Duration sensor which if
> connected to a Davis Vantage Pro2 system needs to go to a spare rain socket
> in the ISS.
> Each 0.01 is equivalent to 36 seconds of sunshine and I have converted
> that to hours and minutes on my web page.
> The next stage was to produce a graph per hour using the rain field in the
> database and to adjust that reading.either with another field in the
> database or when the plot/graph was produced .
> I did have a look in the vantage.py and came across loop_packet['rain'] =
> delta.
> So im asking is this the place to do this or am I totally in the wrong
> place to achieve a field with with rain * 36 in.
> Thanks in Advance
>
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