Try this:

X$third <- rep(X$second[which(!duplicated(X$first))], table(X$first))

On Mon, Jan 12, 2009 at 5:57 AM, Heston Capital <hestoncapital@gmail.com>wrote:

> I am trying to write some code where the factor references its
> previous value, but can't find a solution searching through the
> archive.
>
> > X
>  first second
> 1     A      1
> 2     A      2
> 3     B      3
> 4     B      4
> 5     B      5
> 6     C      6
> 7     C      7
>
> I need a third column, in pseudo code-
>  If value of first=previous value of first:
>        third=previous value of third
>  else third = second
>
> So the third column would look like:
> 0
> 0
> 3
> 3
> 3
> 6
> 6
>
>
> Thanks!
>
> ______________________________________________
> 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.
>



-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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