Peter Dalgaard <[EMAIL PROTECTED]> napsal dne 10.11.2008 14:05:41: > Petr PIKAL wrote: > > Hi > > > > [EMAIL PROTECTED] napsal dne 10.11.2008 13:25:41: > > > >> Hi, > >> I want to sample a block of information. > >> > >> Let's say x is a time series. Using sample(x,5) I get a random sample of > >> length 5 from x. > >> > >> Is it possible to sample consecutive observations, i.e. I sample one > >> observation and also get the next 4 observations? > > > > Easy > > > > sam <- sample(x,1) > > x[sam:(sam+4)] > > > You mean > > sam <- sample(seq_along(x),1) > x[sam:(sam+4)]
Yes, I meant it. Without an example I set my x series as 1:100 so it was in seq order and no need to use seq_along. Petr > > I think this answers the question as posed, but possibly not as meant. > > You might have > > block <- seq_along(x) %/% 5 > > and want to an entire block. This is a little more tricky: > > bl <- sample(unique(block),1) > x[block==bl] > > It gets even trickier if you want to vectorize sampling of multiple > blocks, but let's leave that for now. > > > Regards > > Petr > > > > > > > >> Thanks a lot! > >> > >> Martin > >> -- > >> View this message in context: > > http://www.nabble.com/how-to-sample-a-block- > >> tp20418997p20418997.html > >> Sent from the R help mailing list archive at Nabble.com. > >> > >> ______________________________________________ > >> R-help@r-project.org 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. > > > > ______________________________________________ > > R-help@r-project.org 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. > > > -- > O__ ---- Peter Dalgaard Ă˜ster Farimagsgade 5, Entr.B > c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K > (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 > ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ R-help@r-project.org 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.