Thanks Gabor. On Wed, Jul 28, 2010 at 9:24 PM, Gabor Grothendieck [via R] < ml-node+2305561-610338075-309...@n4.nabble.com<ml-node%2b2305561-610338075-309...@n4.nabble.com> > wrote:
> On Wed, Jul 28, 2010 at 2:10 PM, Raghu <[hidden > email]<http://user/SendEmail.jtp?type=node&node=2305561&i=0>> > wrote: > > > Hi > > > > I have say a large vector of 3500 digits. Initially the digits are 0s and > > > 1s. I need to check for a rule to change some of the 0s to -1s in this > > vector. But once I change a 0 to -1 then I need to start applying the > rule > > to change the next 0 only after I see the next 1 in the vector. > > > > Say for example x = (0,0,0,0,0,0,0,1,0,0,1,1,0,0,1,0,0,0,1) > > I need to traverse from the 9th element to the last ( because the first > > occurrence of 1 is at 8) . Let us assume that according to our rule we > > change the 13th element (only 0s can be changed) to -1. Now we need to go > to > > the next occurrence of 1 (which is 15) and begin the rule application > from > > the 16th till the end of the vector and once replaced a 0 to a -1 then > start > > again from the next 1. How do we code this? I 'feel' recursion is the > best > > possible solution but I am not a programmer and will await experts' > views. > > If this is not a typical R-forum question then my advance apologies. > > > > If you are asking to replace the first 0 after any string of 1s with a > -1 then try this: > > > > replace(x, c(FALSE, diff(x) < 0), -1) > [1] 0 0 0 0 0 0 0 1 -1 0 1 1 -1 0 1 -1 0 0 1 > > ______________________________________________ > [hidden email] <http://user/SendEmail.jtp?type=node&node=2305561&i=1>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. > > > ------------------------------ > View message @ > http://r.789695.n4.nabble.com/how-to-code-it-tp2305489p2305561.html > To start a new topic under R help, email > ml-node+789696-608741344-309...@n4.nabble.com<ml-node%2b789696-608741344-309...@n4.nabble.com> > To unsubscribe from R help, click here< (link removed) >. > > > -- 'Raghu' -- View this message in context: http://r.789695.n4.nabble.com/how-to-code-it-tp2305489p2305585.html Sent from the R help mailing list archive at Nabble.com. [[alternative HTML version deleted]] ______________________________________________ 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.
