[R] how to calculate seasonal mean for temperatures

[Petr PIKAL]

Hi

Something like

aggregate(DF$data, list(quarters(DF$date), format(DF$date, "%Y")), mean)

Regards
Petr

> 
> Hello everybody,
> 
> I need to calculate seasonal means with temperature data for my work. 
> I have 70 files coming from weather stations, which looks like this for
> example:
> 
> startdate <- as.POSIXct("01/01/2006", format = "%d/%m/%Y")
> enddate <- as.POSIXct("05/01/2006", format = "%d/%m/%Y")
> date <- seq(from = startdate, to = enddate, by = "days",format = 
"%d/%m/%Y")
> 
> DF <- data.frame(data=c(2.5,1.4,3.6,0.5,-1.2),date=date)
> 
> With this daily data, I need to calculate seasonal means.
> I mean for season: winter (January,February,March) ; Spring 
(April,May,June)
> ; Summer(July,August,September) and Autumn(October,November,December).
> 
> My main problem is that all my files starts and ends not the same year 
(some
> of them starts 1st January 2006 and ends 31th december 2008, some of 
them
> starts 1st January 2007 and ends 31th December 2011, ...).
> 
> So not the same year, but all of them starts a 1st January and ends a 
31th
> December.
> 
> I'd like first to delete (or ignore) all the first 2 months (January and
> February) and the last month (December) of all my files, because I 
cannot
> calculate a seasonal means for them (not all the 3 months).
> But the problem for the first 2 months is for leap yars (with 29th
> February). For example, if my file starts in 2008, the first 2 months 
will
> not be the same length as files starting in 2007 or 2006. So I cannot 
just
> delete the first lines of my files because there'll be a problem for 
these
> leap years.
> And then, I'd like to calculate my seasonal means on each 3 months (like 
I
> showed you before).
> For example, my object "seasonal means" should look like this: Spring 
2006:
> xx ; Summer 2006: xx, ....... (with xx my seasonal means).
> 
> Have you any idea how to do this? I found functions such like "xts()" 
but it
> need to specify a year, so in my case it couldn't work. I need to 
automatize
> this for all my files, so it shouldn't depend on the start year.
> Thanks a lot! 
> 
> 
> 
> 
> 
> 
> 
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> calculate-seasonal-mean-for-temperatures-tp4638639.html
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> 
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