[R] Duplicates and duplicated

[Andrej Blejec]

Try this

x%in%x[which(y)]

>From your example

> x=c(1,2,3,4,4,5,6,7,8,9)
> y=duplicated(x)
> rbind(x,y)
  [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
x    1    2    3    4    4    5    6    7    8     9
y    0    0    0    0    1    0    0    0    0     0
> which(y)
[1] 5
> x[which(y)]
[1] 4
> x%in%x[which(y)]
 [1] FALSE FALSE FALSE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE

Andrej

--
Andrej Blejec
National Institute of Biology
Vecna pot 111 POB 141
SI-1000 Ljubljana
SLOVENIA
e-mail: andrej.blejec at nib.si
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--------------------------
Organizer of
Applied Statistics 2009 conference
http://conferences.nib.si/AS2009

 
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of christiaan pauw
> Sent: Thursday, May 14, 2009 8:17 AM
> To: r-help at r-project.org
> Subject: [R] Duplicates and duplicated
> 
> Hi everybody.
> I want to identify not only duplicate number but also the original
> number
> that has been duplicated.
> Example:
> x=c(1,2,3,4,4,5,6,7,8,9)
> y=duplicated(x)
> rbind(x,y)
> 
> gives:
>     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
> x    1    2    3    4    4    5    6    7    8     9
> y    0    0    0    0    1    0    0    0    0     0
> 
> i.e. the second 4 [,5] is a duplicate.
> 
> What I want is the first and second 4. i.e [,4] and [,5] to be TRUE
> 
>     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
> x    1    2    3    4    4    5    6    7    8     9
> y    0    0    0    1    1    0    0    0    0     0
> 
> I assume it can be done by sorting the vector and then checking is the
> next
> or the previous entry matches using
> identical() . I am just unsure on how to write such a loop the logic
of
> which (I think) is as follows:
> 
> sort x
> for every value of x check if the next value is identical and return
> TRUE
> (or 1) if it is and FALSE (or 0) if it is not
> AND
> check is the previous value is identical and return TRUE (or 1) if it
> is and
> FALSE (or 0) if it is not
> 
> Im i thinking correct and can some help to write such a function
> 
> regards
> Christiaan
> 
> 	[[alternative HTML version deleted]]
> 
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