R help - Oct 2009 - How to get duplicated items in a vector?

Hi,
> x=c(rep(1,3),rep(3,2))
> x
[1] 1 1 1 3 3
> duplicated(x)
[1] FALSE  TRUE  TRUE FALSE  TRUE
>
As shown in the above code, 'duplicated' doesn't return 'F'
for the
first '1' and first '3' in 'x'. I am wondering if there
is a function
that can return an indicator for any element whether it appears in a
vector twice or more.

Regards,
Peng

Try this:
> x <- c(1, 2, 3, 3, 4, 5)
> ave(x, x, FUN = length) > 1
[1] FALSE FALSE  TRUE  TRUE FALSE FALSE


On Thu, Oct 1, 2009 at 10:42 PM, Peng Yu <pengyu.ut at gmail.com>
wrote:
> Hi,
>
>> x=c(rep(1,3),rep(3,2))
>> x
> [1] 1 1 1 3 3
>> duplicated(x)
> [1] FALSE ?TRUE ?TRUE FALSE ?TRUE
>>
>
> As shown in the above code, 'duplicated' doesn't return
'F' for the
> first '1' and first '3' in 'x'. I am wondering if
there is a function
> that can return an indicator for any element whether it appears in a
> vector twice or more.
>
> Regards,
> Peng
>
> ______________________________________________
> 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.
>

Bill Dunlap
TIBCO Software Inc - Spotfire Division
wdunlap tibco.com  
> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Peng Yu
> Sent: Thursday, October 01, 2009 7:42 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] How to get duplicated items in a vector?
> 
> Hi,
> 
> > x=c(rep(1,3),rep(3,2))
> > x
> [1] 1 1 1 3 3
> > duplicated(x)
> [1] FALSE  TRUE  TRUE FALSE  TRUE
> >
> 
> As shown in the above code, 'duplicated' doesn't return
'F' for the
> first '1' and first '3' in 'x'. I am wondering if
there is a function
> that can return an indicator for any element whether it appears in a
> vector twice or more.
You could use is.element() or %in%, as in
   > x <- rep(3:1, 3:1)
   > x %in% x[duplicated(x)]
   [1]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE

Bill Dunlap
TIBCO Software Inc - Spotfire Division
wdunlap tibco.com 
> 
> Regards,
> Peng
> 
> ______________________________________________
> 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.
>

Try this:
>  x=c(rep(1,3),rep(3,2))
> x
[1] 1 1 1 3 3
> duplicated(x) | duplicated(x, fromLast=TRUE)
[1] TRUE TRUE TRUE TRUE TRUE
>

On Thu, Oct 1, 2009 at 10:42 PM, Peng Yu <pengyu.ut at gmail.com>
wrote:
> Hi,
>
>> x=c(rep(1,3),rep(3,2))
>> x
> [1] 1 1 1 3 3
>> duplicated(x)
> [1] FALSE ?TRUE ?TRUE FALSE ?TRUE
>>
>
> As shown in the above code, 'duplicated' doesn't return
'F' for the
> first '1' and first '3' in 'x'. I am wondering if
there is a function
> that can return an indicator for any element whether it appears in a
> vector twice or more.
>
> Regards,
> Peng
>
> ______________________________________________
> 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.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

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