Plotting an extended variable with Belchertown graphs just like rainTotal

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Maarten van der Hoeven

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May 30, 2020, 6:39:21 AM5/30/20

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Hi,

I wrote an extension to weewx, that calculates the amount of drought (evapotranspiration minus rain). Basilcally, drought is a 'bucket'-type. Every time a rain-tick of an evaotranspiration (ET)-calculation (on top every hour), drought is calculated as ET minus rain. I am talking about a Davis Vantage Pro. It's an extension on schema_extended

I saw that the Belchertown skin calculates rainTotal, to use that variable to draw an accumulated (growing when rain occurs during the year) rain graph.

I also want to plot the drought-variable as an accumulated value, just like rainTotal. Is this possible in the graph.conf file, to achieve this? Or do I need an calculation by myself, and store that accumulated value in another column (for example, droughtyear)?

I have added a column 'drought' to the archive table, also a table is created 'archive_day_drought'. All is populated using the weewx-services; this is working very well. Only question is: how to plot the accumulated drought as a graph.

Archive table (see at the end, drought):

Live data:

+-------------------------+---------+--------+------+
| from_unixtime(dateTime) | drought | ET     | rain |
+-------------------------+---------+--------+------+

| 2020-05-30 12:05:00     |       0 |      0 |    0 |
| 2020-05-30 12:04:00     |       0 |      0 |    0 |
| 2020-05-30 12:03:00     |       0 |      0 |    0 |
| 2020-05-30 12:02:00     |       0 |      0 |    0 |
| 2020-05-30 12:01:00     |       0 |      0 |    0 |
| 2020-05-30 12:00:00     | 0.4826 | 0.4826 |    0 |
| 2020-05-30 11:59:00     |       0 |      0 |    0 |
| 2020-05-30 11:58:00     |       0 |      0 |    0 |
| 2020-05-30 11:57:00     |       0 |      0 |    0 |
+-------------------------+---------+--------+------+

Archive table archive_day_drought, live data:

mysql> select from_unixtime(datetime),min,mintime,max,maxtime,sum,count,wsum,sumtime from archive_day_drought order by datetime desc limit 10;
+-------------------------+--------+------------+---------------------+------------+--------------------+-------+---------------------+---------+
| from_unixtime(datetime) | min    | mintime    | max                 | maxtime    | sum                | count | wsum                | sumtime |
+-------------------------+--------+------------+---------------------+------------+--------------------+-------+---------------------+---------+
| 2020-05-30 00:00:00     |      0 | 1590789660 |              0.4826 | 1590832800 |             1.6256 |   756 |              97.536 |   45360 |
| 2020-05-29 00:00:00     |      0 | 1590703260 |              0.5334 | 1590757200 | 5.206999999999999 | 1440 |              312.42 |   86400 |
| 2020-05-28 00:00:00     |      0 | 1590616860 |              0.5588 | 1590670800 | 5.029200000000001 | 1435 |             301.752 |   86100 |
| 2020-05-27 00:00:00     |      0 | 1590530460 |              0.4826 | 1590577200 |             4.4196 | 1437 | 265.17600000000004 |   86220 |
| 2020-05-26 00:00:00     |      0 | 1590444060 |               0.508 | 1590498000 |              4.572 | 1440 | 274.31999999999994 |   86400 |
| 2020-05-25 00:00:00     | -0.254 | 1590388620 |              0.3302 | 1590415200 | 2.5907999999999998 | 1440 |             155.448 |   86400 |
| 2020-05-24 00:00:00     | -0.254 | 1590312540 | 0.22859999999999997 | 1590307200 | -4.648199999999999 | 1315 | -278.89200000000005 |   78900 |
| 2020-05-23 00:00:00     |      0 | 1590184860 |              0.5334 | 1590235200 | 5.1053999999999995 | 1424 |             306.324 |   85440 |
| 2020-05-22 00:00:00     |      0 | 1590098460 |              0.4064 | 1590148800 | 3.1750000000000003 | 1440 | 190.50000000000003 |   86400 |
| 2020-05-21 00:00:00     |      0 | 1590012060 |              0.5334 | 1590066000 | 4.978400000000001 | 1440 |             298.704 |   86400 |
+-------------------------+--------+------------+---------------------+------------+--------------------+-------+---------------------+---------+
10 rows in set (0.00 sec)

Tom Keffer

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May 30, 2020, 8:46:48 AM5/30/20

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Hello, Maarten

I am not familiar with Belchertown, but wanted to note that there is a 'cumulative' aggregation type. Belchertown may have a different way of doing things, but for a normal WeeWX plot

[[[monthdroughtcum]]]
plot_type = bar
[[[[drought]]]]
aggregate_type = cumulative
label = Drought (cumulative)

would give you a plot of accumulated 'drought' for the month.

-tk

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Maarten van der Hoeven

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May 30, 2020, 3:38:47 PM5/30/20

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Perfect Tom, thanks!

Op zaterdag 30 mei 2020 14:46:48 UTC+2 schreef Tom Keffer:

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