[R] Preparing timestamped data for fourier analysis

From: Pete Cap <peteoutside_at_yahoo.com>
Date: Tue 14 Jun 2005 - 03:16:31 EST


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                 


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