Thank you very much Stephen, but how will aggregate deal with months that
fall outside annual quarters? eg, one extra month at the end of the dataset?

2008/8/18 stephen sefick <ssefick@gmail.com>

> ?aggregate
> may do what you want
>
> On Mon, Aug 18, 2008 at 8:19 AM, Denise Xifara
> <dionysia-kiara.xifaras@st-hildas.ox.ac.uk> wrote:
> > Dear R users,
> >
> > I have a dataframe where column is has countries, column 2 is dates
> > (monthly) for each countrly, the next 10 columns are my factors where I
> have
> > measurements for each country and  for each date.  I have attached a
> sample
> > of the data in csv format with the data for 3 countries.
> >
> > I would like to convert my monthly data into quarterly data, finding the
> > mean over 3 month periods for factors a-i, and the sum for factor j.  My
> > problem is that not all countries have starting date at the beginning of
> a
> > quarter for a particular year, ie some countries start in May or
> September,
> > and also some countries have one extra month, some have two extra months
> so
> > there's no way of deleting some rows with a simple command (I want to get
> > rid of all extra data that does not fall into the quarters for each
> > country), since the amount of data to get rid of for each country varies.
> >
> > I tried for example:
> > i=1
> > denise<-data[((data$country)==unique(data$country[i]),]
> > denise[,2]<- as.Date(denise$date, "%Y-%m-%d")
> > denise2<-denise[order(denise[,2],decreasing=FALSE),]
> > len<-length(denise[,1])
> > limit<-floor(len/3)+1
> > splitter<-rep(1:limit,each=3)
> > spl.dat<-split(denise2,splitter)
> > new.data<-as.matrix(lapply(spl.dat,FUN="mean"))
> >
> > This finds the mean every 3 rows but this doesnt consider the data
> quarterly
> > in a calendar sense.  ie if the data starts in november, it doesnt
> discard
> > the data for november, december and start calculating the means from
> january
> > onwards, until the month where the last quarter finishes, discarding any
> > extra month, or two months at the end.
> >
> > I tried converting my data frame/matrix to a time series but the dates
> are
> > not kept.  I got:
> >
> >>tser<-as.ts(denise)
> > Warning message:
> > In data.matrix(data) : class information lost from one or more columns
> >
> > and column 2 has become a list of numbers rather than dates.
> >
> > I tried:
> >
> >> library(fCalendar)
> >> den.tseries<-as.timeSeries(denise)
> > Warning messages:
> > 1: In .whichFormat(charvec, ...) : Could not determine time(date) format
> > 2: In .whichFormat(charvec, ...) : Could not determine time(date) format
> >> is.timeSeries(den.tseries)
> > [1] TRUE
> >> apply.quarterly(den.tseries,FUN="mean")
> >                   data
> > 1970-01-01 -2.425000000
> > 1970-04-01 -0.557961111
> > 1970-04-28  0.009814815
> >
> > Here, it calculates things quarterly but the the as.timeSeries command
> has
> > assigned its own daily dates to the data, instead of keeping my monthly
> > dates.  Also, I don't understand how it deals with the extra dates.
> >
> > Sorry for the long email,
> > Any help would be very much appreciated,
> > Kind regards,
> > Denise
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
> > and provide commented, minimal, self-contained, reproducible code.
> >
> >
>
>
>
> --
> Let's not spend our time and resources thinking about things that are
> so little or so large that all they really do for us is puff us up and
> make us feel like gods. We are mammals, and have not exhausted the
> annoying little problems of being mammals.
>
>        -K. Mullis
>

	[[alternative HTML version deleted]]

