Dear Luc, You should send this kind of questions to the general mailing list ([EMAIL PROTECTED]) instead of the developer list.
To answer your question: have a look at ?by and ?aggregate HTH, Thierry ------------------------------------------------------------------------ ---- ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest Cel biometrie, methodologie en kwaliteitszorg / Section biometrics, methodology and quality assurance Gaverstraat 4 9500 Geraardsbergen Belgium tel. + 32 54/436 185 [EMAIL PROTECTED] www.inbo.be To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey -----Oorspronkelijk bericht----- Van: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Namens RFTW Verzonden: donderdag 4 september 2008 9:07 Aan: r-devel@r-project.org Onderwerp: [Rd] calculating means per group Hi all I have a very basic question, yet i have not found how to do it. Suppose my dataset looks like this: Year Area value 1 a 20 1 a 25 1 a 28 1 a 31 1 a 23 1 b 25 1 b 28 1 b 23 1 b 19 2 a 25 2 a 23 2 a 24 2 a 26 2 b 27 2 b 28 2 b 20 2 b 25 2 b 28 Now, i want to calculate a MEAN per year per area. How do i do that? With mean(value) i calculate the mean of all values of course. I just need to know how to group year and area correctly. I assume that i can use this grouping in other calculations too, right? Cheers, Luc -- View this message in context: http://www.nabble.com/calculating-means-per-group-tp19271479p19271479.ht ml Sent from the R devel mailing list archive at Nabble.com. ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver weer en binden het INBO onder geen enkel beding, zolang dit bericht niet bevestigd is door een geldig ondertekend document.%CRLF%The views expressed in this message and any annex are purely those of the writer and may not be regarded as stating an official position of INBO, as long as the message is not confirmed by a duly signed document%CRLF% ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
