[R] Annual cumulative sums from time series

[Dimitris Rizopoulos]

maybe something like this:

dat <- data.frame(years=rep(1994:2004, each=10), x=rnorm(110), 
y=rnorm(110))
lapply(split(dat[,-1], dat$years), cumsum)

is what you want.

I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.ac.be/biostat/
     http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Georg Hoermann" <georg.hoermann at gmx.de>
To: <r-help at stat.math.ethz.ch>
Sent: Thursday, February 10, 2005 11:01 AM
Subject: [R] Annual cumulative sums from time series


> Hello world,
>
> I am actually transferring a course in data management for
> students in biology, geography and agriculture
> from statistica to R - it works
> surprisingly well. If anyone is interested in my scratch/notepad
> (in German language), please see
>
> www.hydrology.uni-kiel.de/~schorsch/statistik/statistik_datenauswertung.pdf
>
> (pages 40-52)
>
> The dataset is:
>
> www.hydrology.uni-kiel.de/~schorsch/statistik/erle_stat.csv
>
> It contains a 10 year dataset. So far for introduction, now
> comes the problem:
>
> we often need cumulative *annual* sums (sunshine, precipitation),
> i.e. the sum
> must reset to 0 at the beginning of the year. I know
> of cumsum(), but I do not now how to split the dataset automagically
> into annual pieces so I can cumsum() every year separately.
> I have the strong hope that the solution is one of these
> one-liners which leave the students with eyes wide open in surprise 
> and
> makes them true believers in the power of the command-line 8-).
>
> Thanks & Greetings
> Georg
>
>
> -- 
> Georg Hoermann, Luebeck, Germany
> Tel. 0451/47 70 32, 0172/431 57 15, Penguin #189476
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html
>