we can speed this up a lot > system.time(for (i in 1:2000) ifelse(c(0, diff(data$mydata)) != 1, 0, 1)) user system elapsed 0.122 0.012 0.132 > system.time(for (i in 1:2000) as.numeric( c(0, diff(data$mydata))==1)) user system elapsed 0.073 0.007 0.078 > ifelse(c(0, diff(data$mydata)) != 1, 0, 1) [1] 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 > as.numeric( c(0, diff(data$mydata))==1) [1] 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 >
On Mon, Dec 15, 2014 at 7:18 AM, Jorge I Velez <jorgeivanve...@gmail.com> wrote: > Dear jeff6868, > > Here is one way: > > ifelse(with(data, c(0, diff(mydata))) != 1, 0, 1) > > You could also take a look at ?rle > > HTH, > Jorge.- > > > > On Mon, Dec 15, 2014 at 9:33 PM, jeff6868 <geoffrey_kl...@etu.u-bourgogne.fr >> wrote: >> >> Hello dear R-helpers, >> >> I have a small problem in my algorithm. I have sequences of "0" and "1" >> values in a column of a huge data frame, and I just would like to keep the >> first value of each sequences of "1" values, such like in this example: >> >> data <- >> >> data.frame(mydata=c(0,0,0,1,1,1,1,1,0,0,0,0,1,1,1,0,0,0,0,1,1,1,1,1,1,1),final_wished_data=c(0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0)) >> >> Any easy way to do this? >> >> Thanks everybody! >> >> >> >> >> -- >> View this message in context: >> http://r.789695.n4.nabble.com/keep-only-the-first-value-of-a-numeric-sequence-tp4700774.html >> Sent from the R help mailing list archive at Nabble.com. >> >> ______________________________________________ >> 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. >> > > [[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. ______________________________________________ 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.
