Bill, Josh, and Bert, Thanks for your responses. I still can't quite get this when I use actual dates. Here's an example of what is going wrong:
X=as.data.frame(1:6000) X[2]=seq.POSIXt(ISOdate(2015,11,1),by='hour',length.out=6000) X[3]=sample(100,size=6000,replace=T) Y=xts(X[,3],order.by=X[,2]) decompose(Y) Z=ts(X[,2],frequency=24*365) plot(decompose(Z)) When I specify an actual date/time (rather than just a number as Bill posited), it does not like anything short of a year. This seems like I'm overlooking something obvious, but I can't get this for the life of me... Thanks for your time, r On Wed, Mar 30, 2016 at 1:03 PM, William Dunlap <wdun...@tibco.com> wrote: > You said you specified frequency=96 when you constructed the time > series, but when I do that the decomposition looks reasonable: > > > time <- seq(0,9,by=1/96) # 15-minute intervals, assuming time unit is day > > measurement <- sqrt(time) + 1/(1.2+sin(time*2*pi)) + > rnorm(length(time),0,.3) > > plot(decompose(ts(measurement, frequency=96))) > > How is your code different from the above? > > > > Bill Dunlap > TIBCO Software > wdunlap tibco.com > > On Wed, Mar 30, 2016 at 8:03 AM, Ryan Utz <utz.r...@gmail.com> wrote: > >> Hello, >> >> I have a time series that represents data sampled every 15-minutes. The >> data currently run from November through February, 8623 total readings. >> There are definitely daily periodic trends and non-stationary long-term >> trends. I would love to decompose this using basic time series analysis. >> >> However, every time I attempt decomposition, I get the >> >> Error in decompose( ) : time series has no or less than 2 periods >> >> Is it only possible to do basic time-series analysis if you have a year or >> more worth of data? That seems absurd to me, since there is definite >> periodicity and the data are a time series. I have tried every manner of >> specifying frequency= with no luck (96 does not work). All manner of >> searching for help has turned up fruitless. >> >> Can I only do this after I wait another year or two? >> >> Thanks, >> Ryan >> >> -- >> >> Ryan Utz, Ph.D. >> Assistant professor of water resources >> *chatham**UNIVERSITY* >> Home/Cell: (724) 272-7769 >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> 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. >> > > -- Ryan Utz, Ph.D. Assistant professor of water resources *chatham**UNIVERSITY* Home/Cell: (724) 272-7769 [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.