As you've discovered, temperature conversion functions are not distributive. That is, F_to_C(68F - 50F) is not equal to F_to_C(68F) - F_to_C(50F).
No, there is no group_temperaturediff. The tag $trend has a problem similar to yours. It needs to calculate the difference between the temperature some time ago, and the current temperature. It solves the problem the same way you are: perform the conversion just before use. I think your approach is very sensible. -tk On Fri, Nov 20, 2020 at 11:22 AM Karen K <[email protected]> wrote: > I write the driver for Wetternetz Sachsen, and I have to upload some > temperature differences there. > > And I wonder what is the *intended way* to convert those differences from > one unit to another. > > The template for a restful service driver says that I have to put code to > read or calculate additional values into the "get_record" function, where > the archive unit system is used. The conversion to the target unit system I > have to put into the "format_url" function. > > Temperatures and temperature differences are converted in a different way > because of the offset between the units. > > But I found no "group_temperaturediff" or "group_temperaturerate" unit > group, that could cover that. > > Because I did not know I put the code to read the start and end > temperature of the given interval into the "get_record" function. No > difference is calculated there. In "format_url" function first the data > record is converted into the target unit system and then the temperature > difference is calculated. > > Shall I do so or is there a better way? > > -- > You received this message because you are subscribed to the Google Groups > "weewx-development" 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-development/d0f8e51c-9474-4287-b067-aae6524fa21cn%40googlegroups.com > <https://groups.google.com/d/msgid/weewx-development/d0f8e51c-9474-4287-b067-aae6524fa21cn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "weewx-development" 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-development/CAPq0zEBOrxc%2BdZVRTCUFnbvYDwDZ7QCrRsq%2BH1MaY3Wy0zguXw%40mail.gmail.com.
