> -----Original Message-----
> From: r-help-boun...@r-project.org
> [mailto:r-help-boun...@r-project.org] On Behalf Of Petr PIKAL
> Sent: Thursday, October 07, 2010 12:13 AM
> To: rivercode
> Cc: r-help@r-project.org
> Subject: [R] Odp: Vector replace 0 elements without using a loop
>
> Hi
>
>
> r-help-boun...@r-project.org napsal dne 07.10.2010 07:16:01:
>
> >
> > Hi,
> >
> > With a vector like:
> >
> > x = c (22, 23, 22.5, 0,0,24, 0, 23.2, 23.5, 0,0,0, 26)
> >
> > How can I replace the 0's with the previous last value
> without looping
> > through the vector ?
>
> Change your zeroes to NA values
> x[x==0]<-NA
>
> use na.locf function from zoo package
>
> library(zoo)
>
> x<-na.locf(x)
>
> Regards
> Petr
Or if you want to do it from scratch try defining the
following function. For each element of the logical
vector x it returns the index of the last TRUE
entry up to that point.
indexOfMostRecentTrueEntry <- function (x)
{
stopifnot(is.logical(x))
x <- x & !is.na(x) # treat NA's as FALSE's
retval <- cummax(seq_along(x) * x)
retval[retval == 0] <- NA # in case x starts with FALSE
retval
}
and get your result with
x[indexOfMostRecentTrueEntry(x!=0)]
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
>
>
> >
> > Something tells me I am missing the obvious.
> >
> > Thanks,
> > Chris
> > --
> > View this message in context:
> http://r.789695.n4.nabble.com/Vector-replace-0-
> > elements-without-using-a-loop-tp2966191p2966191.html
> > Sent from the R help mailing list archive at Nabble.com.
> >
> > ______________________________________________
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>
> ______________________________________________
> R-help@r-project.org mailing list
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