On Wed, Jul 28, 2010 at 2:18 PM, Henrique Dallazuanna <wwwhsd@gmail.com>wrote:

> You've tried:
>
> diff(c(0, x)) ?
>

This is clever, but not quite what he's asking for--it converts a sequence
of 1's into a 1 followed by zeroes.

Jonathan



>
> On Wed, Jul 28, 2010 at 3:10 PM, Raghu <r.raghuraman@gmail.com> 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.
> >
> > Many thx
> > --
> > 'Raghu'
> >
> >        [[alternative HTML version deleted]]
> >
> > ______________________________________________
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> > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
>
>
>
> --
> Henrique Dallazuanna
> Curitiba-Paraná-Brasil
> 25° 25' 40" S 49° 16' 22" O
>
>        [[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.
>
>

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