Change Barometer units?

[duke]

I want to move away from 'mb' for my unit of measure and use 'hpa'. As they are essentially the same unit, is this possible without Cumulus having a panic attack?

[steve]

Yes, that particular units change is fine.

[duke]

Ok, thanks Steve, done. Out of interest, do you know of any one that has tried or know what is involved to change from 'mph/miles' to the modern 'km/km/h'?

[steve]

You would have to convert the values in all of the files in the data folder. Not too hard, just a bit tedious. Manually edit the .ini files, and use Excel or whatever to edit the comma separated log files (select the appropriate columns and multiply the values by 1.6). Make sure Excel doesn't alter the date format.

[duke]

That does not sound too bad, and not as bad as I had imagined. I'll install a second copy of Cumulus, convert my files and give it ago!

I'll be using the 'Apache OpenOffice Calc'.

[mcrossley]

Make sure Excel doesn't alter the date format.

My tip is to make sure the date/time column imports as 'text' rather than 'general'.

[duke]

I'll bear it mind Mark

[sfws]

I'll be using the 'Apache OpenOffice Calc'.

Apache Open Office (like Libre Office) 'Calc' is easy to use for importing in text without any assumptions about 'number format'. I believe the default is not to recognise any special number formats, but it should display an import screen with all options.
'Text CSV' is a standard optional saving format in Calc. (Sentence amended in edit of this post) If you use 'Save as' you can alter extension to '.txt' from '.csv' and select 'Edit filter options' to select your preferred field delimiter (e.g. ',').

Some years ago now I had about half a year of Cumulus derived data, and I easily used 'Calc' to import a couple of years of pre-Cumulus data. (Back then I had to use a beta release to get a version of Calc that permitted enough rows for all the processing I wanted to do, but that is not a problem now with the current versions from Apache and the Document Foundation respectively). I did edit some of my wind data using 'Calc' applying a paste special multiplier, but it was just to compensate for a change in mast height, not for a change of units.

Mark has responded and you have replied while I composed this (I'm busy with something else too), but I think it still is reassurance to you...

[duke]

Ok thanks,

Steve, I have two thoughts on this.

1/ if I install a second instance of Cumulus and start it fresh (no past data) with Km set, can I 'drop in' the converted data as and when I complete it?

2/ if I install a second instance of Cumulus with all the past data but set to km, will it not read the old 'mph' figure as though it were 'km'? I assume Cumulus does not know any difference, it's just a figure - right? And again, I can then convert the past data in this instance of Cumulus as and when but all new data will be correct.

Did that make sense

I prefer the No2.

[steve]

Merging in the old data may prove tricky, so yes, if you don't want to convert all the data first, then go for option 2; I think that should be OK.

[duke]

Thanks Steve.

[steve]

Sorry, I've realised that I wasn't clear in what I said. You have to at least convert the ini files immediately, as otherwise you might be breaking wind speed records when you shouldn't (e.g. 31 kph is not higher than 30 mph). You may have realised this, of course.

[duke]

My intentions are to install a copy of Cumulus into a new directory (cumulus_metric), copy the data folder and my existing '.ini' and then before any new data is recorded change the units from 'mph' to 'km/h' on the station set up screen.

[steve]

Yes, that won't work. Or at least it has the risk that you will start breaking records when you haven't actually broken them, as in my example above. To avoid this possibility, you need to convert the values in the ini files before you run the new copy.

[duke]

Sorry, being a bit slow this morning, I was only thinking of 'Cumulus.ini'.

So to be clear, other than 'Cumulus.ini' we are talking,

alltime.ini
month.ini
monthalltime.ini
today.ini
year.ini
yesterday.ini

And obviously I must make a note of exactly what time/date I start the new 'metric' Cumulus to know what date/time to convert the files up to.