[R] subsets of vector

[Gabor Grothendieck]

Use rle:

with(rle(x), data.frame(value = values,
  start = cumsum(lengths)-lengths+1, end = cumsum(lengths))[lengths > 1,])

On 3/23/06, Fred J. <phddas at yahoo.com> wrote:
> dear R users
>  I have been trying a lot to get this task accomplished but need your help.
>
>  input:
>  x <- c(3,3,4,4,4,4,5,7,7,0,1,1,2,2,2)
>
>  desired output
>  3 1 2
>  4 3 6
>  7 8 9
>  ...
>  which means,
>  3 is repeated at index 1:2
>  4 is repeated at index 3:6
>  ...
>  my effort has not been that good.
>  a <- !c(NA,diff(x));
>  b <- which(a==1);
>  a[b-1]=1;
>  cbind(x,a);
>
>  or
>  sp <- (seq(diff(x))[!!cumsum(!!diff(x))])[1];sp
>  #first locations of duplicates
>  l <- which(diff(x[sp:length(x)])==0); l
>  m <- which(diff(l)==1);m
>  flod <- l[m]+1; print(flod);
>
>
>  thank you
>
> ---------------------------------
>
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>
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