[R] Is there a neat R trick for this?

[Nordlund, Dan (DSHS/RDA)]

Another option is

which(y %in% x)


Dan

Daniel J. Nordlund
Washington State Department of Social and Health Services
Planning, Performance, and Accountability
Research and Data Analysis Division
Olympia, WA 98504-5204

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Pascal Oettli
> Sent: Tuesday, February 12, 2013 2:21 AM
> To: Robert Latest
> Cc: r-help at r-project.org
> Subject: Re: [R] Is there a neat R trick for this?
> 
> Hello,
> 
> ?match
> 
>  > x <- c(4,5,6)
>  > y <- c(10,1,5,12,4,13,14)
>  > match(x,y)
> [1]  5  3 NA
> 
> Hope this helps,
> Pascal
> 
> 
> Le 12/02/2013 19:09, Robert Latest a écrit :
> > Hello all,
> >
> > given two vectors X and Y I'd like to receive a vector Z which
> > contains, for each element of X, the index of the corresponding
> > element in Y (or NA if that element isn't in Y).
> >
> > Example:
> >
> > x <- c(4,5,6)
> > y <- c(10,1,5,12,4,13,14)
> >
> > z <- findIndexIn(x, y)
> > z
> > [1] 5 3 NA
> >
> > 1st element of z is 5, because the 1st element of x is at the 5th
> position in y
> > 2nd element of z is 3, because the 2nd element of x is at the 3rd
> position in y
> > 3rd element of z is NA, because the 3rd element of x is not in y
> >
> > Of course I can write the function findIndexIn() using a for loop,
> but
> > in 80% of cases when I felt the urge to use "for" in R it turned out
> > that there was already some builtin operator or function that did the
> > trick.
> >
> > Suggestions, anyone?
> > Thanks,
> >
> > robert
> >
> > ______________________________________________
> > R-help at 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.
> >
> 
> ______________________________________________
> R-help at 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.