I believe that FFT is not appropriate. However Lomb-Scargle periodogram could be used.
Sincerely Milos Zarkovic ****************************************************** Milos Zarkovic MD, Ph.D. Associate Professor of Internal Medicine Institute of Endocrinology Dr Subotica 13 11000 Beograd Serbia Tel +381-63-202-925 Fax +381-11-685-357 Email [EMAIL PROTECTED] ****************************************************** ----- Original Message ----- From: "Pete Cap" <[EMAIL PROTECTED]> To: <r-help@stat.math.ethz.ch> Sent: Monday, June 13, 2005 7:16 PM Subject: [R] Preparing timestamped data for fourier analysis > Greetings all, > > I'm working on a project trying to apply fourier analysis to timestamped > router logs, using R to perform the analysis. The idea is to determine if > any type of traffic (say, outgoing ICMP requests) has strong periodic > features because it may indicate a compromise somewhere on the network. > > The FFT requires all data points to be evenly spaced, but the recorded > events do not occur at a consistent constant dt, so I need to "zero pad" > the data. I can do this for small data sets (say, one day's worth of > traffic) in excel. > > However, I am now attempting it on a large scale using a 25-day router > log, which should have 2,160,000 records. The log actually contains only > 56,725 records. > > So, I'm looking for ways in which to pad the data in R. If anyone could > just point me at the right man pages to read that would be itself a great > help. > > Thanks in advance, > > Pete > > > --------------------------------- > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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