Barth B. Riley
bbriley at chestnut.org
Fri Nov 25 20:51:26 CET 2011
Z[f] would return the fth values in z. That is, if f = c(1,2) z[f] would return the first and second elements of z. The original intent was to obtain the indices in z corresponding to the values in f.
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Patrick Burns
Sent: Friday, November 25, 2011 1:41 PM
To: r-help at r-project.org; ihok at hotmail.com
Subject: Re: [R] perfectionism
Did you try:
On 25/11/2011 19:23, Jack Tanner wrote:
> I have a named vector:
>> z<- c(1, 2, 3, 2)
>> names(z)<- c("a","b","c","b")
>> f<- c("b","c")
> I want to know the index in z of the first occurrence of each of the values in f.
> One implementation is
>> sapply(f, function(x) which(names(z)==x))
> b c
> 2 3
> Is which() smart enough to stop when it finds in z the first occurrence of every
> value from f, or does it search through all the values in z only to report the
> first one?
> Are some more elegant ways of writing this code?
> Just curious.
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
pburns at pburns.seanet.com
(home of 'Some hints for the R beginner'
and 'The R Inferno')
R-help at r-project.org mailing list
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
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