How about this?
value.vec[which.vec]
HTH,
Jorge
On Tue, Dec 23, 2008 at 9:52 PM, Sean Zhang wrote:
> Dear R-Helpers:
>
> I am a entry level user of R.
>
> Have the following question. Many thanks in advance.
>
>
> # value.vec stores values
> value.vec <- c('a','b','c')
> # which.vec stores the locations/indexs of values in value.vec.
> which.vec <- c(3, 2, 2, 1)
> # How can I obtain the following vector based on the value.vec and
> which.vec
> mentioned above
> # vector.I.want <- c('c', 'b', 'b', 'a')
> # 3 2 2 1
>
>
> # I try to avoid using the following loop to achieve the goal because the
> which.vec in reality will be very long
>
> vector.I.want <- rep(NA,length(which.vec))
> for (i in 1:length(which.vec))
> { vector.I.want[i] <- value.vec[which.vec[i]] }
>
> # is there a faster way than looping?
>
> Thanks in advance.
>
> -Sean
>
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>
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