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" <[EMAIL PROTECTED]>
To: <r-help@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@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
______________________________________________ R-help@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
