[weewx-user] Re: Keeping custom software calcs over update
Just to follow up. I changed the group of extraTemp1 to group_degree_day in units.py. that is a workaround for the time being. I'd forgotten I'd done that before and explains why it appeared broken on update. -- 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 weewx-user+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[weewx-user] Re: Keeping custom software calcs over update
Actually, I think I may have told you a fib. Whilst it is true that StdWXCalculate will first apply a conversion to US units and then later a conversion back to the original unit system, such a 'double conversion' has no net effect on a temperature difference (converting a difference of say 10C to F will give a value that is wrong (in this case 50F) but when this wrong value is converted back to C you get the original C value (again in this case 10C)). The 'double conversion' is not the source of the error but rather the final conversion is. You are using METRICWX units in your database so StdWXCalculate receives packets with temperature values in C. StdWXCalculate converts these to F (the first conversion to US units) and then does its calculations. So your calc_extraTemp1() method calculates extraTemp1 in F. When StdWXCalculate is finished calculating it converts the packet from US units back to METRICWX so your extraTemp1 is converted to C, but because extraTemp1 is a temperature difference the resulting C value is incorrect. This is what you are seeing now, whilst there have been a number of changes to StdWXCalculate since 3.5.0 was released (March 2016) I don't believe any of these change would account for why your approach no longer works. One good thing though, the realisation that the 'double conversion' has no net effect means that the StdCalibrate approach should work. I ran up a machine and loaded weeWX 3.5.0 with a METRICWX database and the StdCalibrate approach gave an extraTemp1 with the correct value and units. As long as you don't want to display extraTemp1 in F it should do what you want. Gary On Sunday, 12 March 2017 06:36:44 UTC+10, Karl Grant wrote: > > Thanks for your detailed reply. It was working in 3.5, though I didn't > document any other changes. > Now that I'm typing I remember sonething about using degree days as a unit > as that converts okay. > Iif I get time I might look at creating a temperature difference group -- 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 weewx-user+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[weewx-user] Re: Keeping custom software calcs over update
Thanks for your detailed reply. It was working in 3.5, though I didn't document any other changes. Now that I'm typing I remember sonething about using degree days as a unit as that converts okay. Iif I get time I might look at creating a temperature difference group -- 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 weewx-user+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[weewx-user] Re: Keeping custom software calcs over update
Hi, Your problem is nothing to do with the WMR200 driver but rather the internal workings of the StdWXCalculate service. Since you have your hands in wxservices.py, have a look at the do_calculations() method (circa line 174), you will see that the data packet provided to StdWXCalculate is converted to US units before the calculations are done and then converted back to the archive unit system before exiting. This is what is causing your problems. WeeWX does not know how to convert a temperature difference between F and C and vice versa so your extraTemp1 field is getting a double conversion as if it was an absolute (as opposed to differential) F value. There is little you can do without further hacking of wxservices.py, you could save a copy of extraTemp1 at the start of the method before the conversion and then overwrite the incorrect value in the packet as the last thing before the method exits but that is getting messy. You are really just making yourself more of an orphan. Unfortunately this also means that the StdCalibrate suggestion I made will also not work as StdCalibrate does its stuff before StdWXCalculate so it will suffer from the exact same problem. If you were only using the differenc in a report I wuld suggest doing the calculation with some in-line python in a template but you appear to want to plot the data, that means it must be in the archive. Gary On Saturday, 11 March 2017 07:41:57 UTC+10, Karl Grant wrote: > > I might try that, in the meantime I patch wxservices.py with > def calc_extraTemp1(self, data, data_type): > if 'inTemp' in data and 'outTemp' in data: >try: > data['extraTemp1']= round(data['inTemp'] - data['outTemp' > ],1) >except: > pass > > > I needed to use the try/except as it was crashing if there was > incorrect/null data in outTemp. This worked perfectly in 3.5, now I'm back > to having problems with F -> C conversion. My db is in MetricWX, > It appears that WeeWx is still working with degF, before conversion, > > Data InTemp OutTemp CalcDifff > ActDiff InF OutF DiffF DiffFtoC > 2017-03-08 23:31:00 22.49.1 -4.5 22.40 9.10 > -4.50 > 13.3 72.32 48.38 23.94 -4.48 > 2017-03-08 23:41:00 22.49.1 -4.5 22.40 9.10 > -4.50 > 13.3 72.32 48.38 23.94 -4.48 > 2017-03-08 23:51:01 22.49.1 -4.5 22.40 9.10 > -4.50 > 13.3 72.32 48.38 23.94 -4.48 > Is it anything to do with changes related to the wrm200 driver? > > On Wednesday, 8 March 2017 23:55:04 UTC, gjr80 wrote: >> >> Hi, >> >> One approach for a simple calculation like this could be to use the >> StdCalibrate service to set extraTemp1. In weewx.conf something >> like(untested): >> >> [StdCalibrate] >> [[Corrections]] >> extraTemp1 = inTemp - outTemp >> >> This will not be overwritten during upgrade and should achieve the same >> result. One thing to be aware of when using temperature differences is that >> weewx unit conversion will not work on a temperature difference. For >> example, if the driver for your station emits F and your database uses US >> units, but you try to display extraTemp1 in C it will be wrong. If you only >> display F you will be fine. >> >> 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 weewx-user+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[weewx-user] Re: Keeping custom software calcs over update
I might try that, in the meantime I patch wxservices.py with def calc_extraTemp1(self, data, data_type): if 'inTemp' in data and 'outTemp' in data: try: data['extraTemp1']= round(data['inTemp'] - data['outTemp'],1 ) except: pass I needed to use the try/except as it was crashing if there was incorrect/null data in outTemp. This worked perfectly in 3.5, now I'm back to having problems with F -> C conversion. My db is in MetricWX, It appears that WeeWx is still working with degF, before conversion, Data InTemp OutTemp CalcDifff ActDiff InF OutF DiffF DiffFtoC 2017-03-08 23:31:00 22.49.1 -4.5 22.40 9.10 -4.50 13.3 72.32 48.38 23.94 -4.48 2017-03-08 23:41:00 22.49.1 -4.5 22.40 9.10 -4.50 13.3 72.32 48.38 23.94 -4.48 2017-03-08 23:51:01 22.49.1 -4.5 22.40 9.10 -4.50 13.3 72.32 48.38 23.94 -4.48 Is it anything to do with changes related to the wrm200 driver? On Wednesday, 8 March 2017 23:55:04 UTC, gjr80 wrote: > > Hi, > > One approach for a simple calculation like this could be to use the > StdCalibrate service to set extraTemp1. In weewx.conf something > like(untested): > > [StdCalibrate] > [[Corrections]] > extraTemp1 = inTemp - outTemp > > This will not be overwritten during upgrade and should achieve the same > result. One thing to be aware of when using temperature differences is that > weewx unit conversion will not work on a temperature difference. For > example, if the driver for your station emits F and your database uses US > units, but you try to display extraTemp1 in C it will be wrong. If you only > display F you will be fine. > > 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 weewx-user+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
