Re: [R] Preparing timestamped data for fourier analysis
Milos Zarkovic [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] I believe that FFT is not appropriate. However Lomb-Scargle periodogram could be used. This may interest you: (Preprint of submitted paper) Detecting periodic patterns in unevenly spaced gene expression time series using Lomb-Scargle periodograms. http://research.stowers-institute.org/bioinfo/PDF/m2005_lomb-scargle_submitted.pdf R code here http://research.stowers-institute.org/efg/2005/LombScargle/ efg __ 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] 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
Re: [R] Preparing timestamped data for fourier analysis
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
