Thanks Matt, I will try putting the other rule into this.
On Wed, Jul 28, 2010 at 9:06 PM, Matt Shotwell <shotw...@musc.edu> wrote:
> If I take your meaning correctly, you want something like this.
> > x <- c(0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0,
> + 1)
> > easy <- function(x) {
> + state <- 0
> + for (i in 1:length(x)) {
> + if (x[i] == 0)
> + x[i] <- state
> + state <- 0
> + if (x[i] == 1)
> + state <- -1
> + }
> + x
> + }
> > easy(x)
> [1] 0 0 0 0 0 0 0 1 -1 0 1 1 -1 0 1 -1 0 0 1
>
> -Matt
>
>
> On Wed, 2010-07-28 at 14:10 -0400, Raghu 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
>
> --
> Matthew S. Shotwell
> Graduate Student
> Division of Biostatistics and Epidemiology
> Medical University of South Carolina
>
>
--
'Raghu'
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