On Tuesday, 10 August 2021 at 08:37:42 UTC+10 [email protected] wrote: > Here is my output running weewxd directly, I see three lines which show > lightning_distance to be None, which is expected from corrections, but the > following three lines show lightning_distance to be 11.999... It appears > the correction " lightning_distance = lightning_distance if > lightning_strike_count > 0 else None" is working but being ignored in final > output to graph and database. Any additional thoughts? >
The reason you see no change to lightning_distance for some packets is that for those packets lightning_strike_count does not exist so your calibration expression fails and no change is made, in other words lightning_distance remains as it was 11.9999999954. Why does this happen, in layman's terms when lightning_strike_count is not in the loop packet the calibration expression in effect has an unknown variable (lightning_strike_count) and the calibration expression raises an error. The StdCalibrate service which handles the calibration expressions catches that error and discards that calibration expression. Given the limitations of the StdCalibrate service I am not aware of any calibration expression that would do as you want, of course a WeeWX and python wizard might come along an prove me wrong! My thoughts on a solution, unless there is a simple solution in your WeeWX driver or elsewhere upstream of WeeWX I would be writing your own WeeWX service to look at the packet and make the necessary correction. This way you can use a bit of python code to do exactly what you want and you won't be limited by the single line expressions as used by StdCalibrate. All up it should take no more than 10 lines of code. The service could be a data_service or process_service (refer weewx.conf [Engine] [[Services]]) but would need to appear before StdArchive is called. The advantage of your own service is that there is no need to change any one else's code (eg WeeWX driver, upstream code) so you will not have your changes lost during an upgrade (WeeWX or otherwise). Gary -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/337dd140-effa-4c89-be49-24c64eedc01bn%40googlegroups.com.
