Hi without beeing specific in spectrum analysis you will get frequencies and spectral densities fro spectrum()
>From help page An object of class "spec", which is a list containing at least the following components: freq vector of frequencies at which the spectral density is estimated. (Possibly approximate Fourier frequencies.) The units are the reciprocal of cycles per unit time (and not per observation spacing): see Details below. spec Vector (for univariate series) or matrix (for multivariate series) of estimates of the spectral density at frequencies corresponding to freq. <snip> This is the important part: **The result is returned invisibly if plot is true.** So if you call spectrum(data) you will get plot but in case sp <- spectrum(data) you will get also object sp which has above mentioned components. Actual periods are obtainable by n/sp$freq HTH Petr On 8 Jan 2007 at 17:12, Georg Hoermann wrote: Date sent: Mon, 08 Jan 2007 17:12:34 +0100 From: Georg Hoermann <[EMAIL PROTECTED]> To: r-help@stat.math.ethz.ch Subject: [R] Simple spectral analysis > Hello world, > > I am actually trying to transfer a lecture from Statistica to > R and I ran into problems with spectral analysis, I think I > just don't get it 8-( > (The posting from "FFT, frequs, magnitudes, phases" from 2005 > did not enlighten me) > > As a starter for the students I have a 10year data set of air > temperature with daily values and I try to > get a periodogram where the annual period (365 days) should be clearly > visible (in statistica I can get the frequencies and the period). I > tried the spectrum() and pgram() functions, but did not find a way > through... The final aim would be to get the periodogram (and the > residuals from the reassembled data set...) > > Thanks and greetings, > Georg > > The data set: > > air = > read.csv("http://www.hydrology.uni-kiel.de/~schorsch/air_temp.csv") > airtemp = ts(T_air, start=c(1989,1), freq = 365) plot(airtemp) > > > -- > Georg Hoermann, Dep. of Hydrology, Ecology, Kiel University, Germany > +49/431/23761412, mo: +49/171/4995884, icq:348340729, skype: ghoermann > > ______________________________________________ > 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 and provide commented, > minimal, self-contained, reproducible code. Petr Pikal [EMAIL PROTECTED] ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code.