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Atte Tenkanen

2006-Aug-16 07:42 UTC

[R] How to remove similar successive objects from a vector?

Is there some (much) more efficient way to do this?

VECTOR=c(3,2,4,5,5,3,3,5,1,6,6);
NEWVECTOR=VECTOR[1];

for(i in 1:(length(VECTOR)-1))
{
	if((identical(VECTOR[i], VECTOR[i+1]))==FALSE){
		NEWVECTOR=c(NEWVECTOR,VECTOR[i+1])}
}
> VECTOR
 [1] 3 2 4 5 5 3 3 5 1 6 6> NEWVECTOR[1] 3 2 4 5 3 5 1 6

_______________________________
Atte Tenkanen
University of Turku, Finland

Dimitris Rizopoulos

2006-Aug-16 07:57 UTC

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[R] How to remove similar successive objects from a vector?

try something like the following:

x <- c(3,3,2,4,5,5,3,3,5,1,6,6)
#########
nx <- length(x)
ind <- c(TRUE, (x[1:(nx-1)] - x[2:nx]) != 0)
x[ind]


I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Atte Tenkanen" <attenka at utu.fi>
To: <r-help at stat.math.ethz.ch>
Sent: Wednesday, August 16, 2006 9:42 AM
Subject: [R] How to remove similar successive objects from a vector?

> Is there some (much) more efficient way to do this?
>
> VECTOR=c(3,2,4,5,5,3,3,5,1,6,6);
> NEWVECTOR=VECTOR[1];
>
> for(i in 1:(length(VECTOR)-1))
> {
> if((identical(VECTOR[i], VECTOR[i+1]))==FALSE){
> NEWVECTOR=c(NEWVECTOR,VECTOR[i+1])}
> }
>
>> VECTOR
> [1] 3 2 4 5 5 3 3 5 1 6 6
>> NEWVECTOR
> [1] 3 2 4 5 3 5 1 6
>
> _______________________________
> Atte Tenkanen
> University of Turku, Finland
>
> ______________________________________________
> R-help at stat.math.ethz.ch 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.
> 

Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm

Jacques VESLOT

2006-Aug-16 08:01 UTC

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[R] How to remove similar successive objects from a vector?

VECTOR=c(3,2,2,3,4,4,5,5,5,3,3,3,5,1,6,6)
NEWVECTOR <- ifelse(VECTOR[-length(VECTOR)]==VECTOR[-1],NA,VECTOR)
NEWVECTOR[!is.na(NEWVECTOR)]
[1] 3 2 3 4 5 3 5 1

-------------------------------------------------------------------
Jacques VESLOT

CNRS UMR 8090
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1 rue du Professeur Calmette
B.P. 245
59019 Lille Cedex

Tel : 33 (0)3.20.87.10.44
Fax : 33 (0)3.20.87.10.31

http://www-good.ibl.fr
-------------------------------------------------------------------

Atte Tenkanen a ?crit :> Is there some (much) more efficient way to do this?
> 
> VECTOR=c(3,2,4,5,5,3,3,5,1,6,6);
> NEWVECTOR=VECTOR[1];
> 
> for(i in 1:(length(VECTOR)-1))
> {
> 	if((identical(VECTOR[i], VECTOR[i+1]))==FALSE){
> 		NEWVECTOR=c(NEWVECTOR,VECTOR[i+1])}
> }
> 
> 
>>VECTOR
> 
>  [1] 3 2 4 5 5 3 3 5 1 6 6
> 
>>NEWVECTOR
> 
> [1] 3 2 4 5 3 5 1 6
> 
> _______________________________
> Atte Tenkanen
> University of Turku, Finland
> 
> ______________________________________________
> R-help at stat.math.ethz.ch 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.
>

Jarimatti Valkonen

2006-Aug-16 08:05 UTC

head link

[R] How to remove similar successive objects from a vector?

On Wed, Aug 16, 2006 at 10:42:35AM +0300, Atte Tenkanen
wrote:> Is there some (much) more efficient way to do this?
> 
> VECTOR=c(3,2,4,5,5,3,3,5,1,6,6);
> NEWVECTOR=VECTOR[1];
> 
> for(i in 1:(length(VECTOR)-1))
> {
> 	if((identical(VECTOR[i], VECTOR[i+1]))==FALSE){
> 		NEWVECTOR=c(NEWVECTOR,VECTOR[i+1])}
> }
> 
> > VECTOR
>  [1] 3 2 4 5 5 3 3 5 1 6 6
> > NEWVECTOR
> [1] 3 2 4 5 3 5 1 6
How about rle? rle(VECTOR)$values should do the same thing. Don't know
about efficiency, though.

-- 
Jarimatti Valkonen

Gavin Simpson

2006-Aug-16 08:05 UTC

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[R] How to remove similar successive objects from a vector?

On Wed, 2006-08-16 at 10:42 +0300, Atte Tenkanen wrote:> Is there some (much) more efficient way to do this?
> 
> VECTOR=c(3,2,4,5,5,3,3,5,1,6,6);
> NEWVECTOR=VECTOR[1];
> 
> for(i in 1:(length(VECTOR)-1))
> {
> 	if((identical(VECTOR[i], VECTOR[i+1]))==FALSE){
> 		NEWVECTOR=c(NEWVECTOR,VECTOR[i+1])}
> }
> 
> > VECTOR
>  [1] 3 2 4 5 5 3 3 5 1 6 6
> > NEWVECTOR
> [1] 3 2 4 5 3 5 1 6
> 
> _______________________________
> Atte Tenkanen
Is this what you mean?

x <- c(3, 2, 4, 5, 5, 3, 3, 5, 1, 6, 6)
x.wanted <- c(3, 2, 4, 5, 3, 5, 1, 6)

X <- x[diff(x) != 0]

all.equal(x.wanted, X) # check it works

G
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Atte Tenkanen

2006-Aug-16 10:01 UTC

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[R] How to remove similar successive objects from a vector?

Thanks for all respondents!

I wasn't precise enough, when I enclosed my example. In fact, I need a
version which works with all kinds of symbolic data, not only with
numbers. So these versions

rle(VECTOR)$values

and

VECTOR=c(3,2,2,3,4,4,5,5,5,3,3,3,5,1,6,6)
NEWVECTOR <- ifelse(VECTOR[-length(VECTOR)]==VECTOR[-1],NA,VECTOR)
NEWVECTOR[!is.na(NEWVECTOR)]

answered to my needs.

I made a test and the first version was 2.5x faster with my data, but
both works enough fast.

Atte

On Wed, 2006-08-16 at 08:58 +0100, Patrick Burns wrote:> I think
> 
> rle(VECTOR)$values
> 
> will get you what you want.
> 
> Patrick Burns
> patrick at burns-stat.com
> +44 (0)20 8525 0696
> http://www.burns-stat.com
> (home of S Poetry and "A Guide for the Unwilling S User")
> 
> Atte Tenkanen wrote:
> 
> >Is there some (much) more efficient way to do this?
> >
> >VECTOR=c(3,2,4,5,5,3,3,5,1,6,6);
> >NEWVECTOR=VECTOR[1];
> >
> >for(i in 1:(length(VECTOR)-1))
> >{
> >	if((identical(VECTOR[i], VECTOR[i+1]))==FALSE){
> >		NEWVECTOR=c(NEWVECTOR,VECTOR[i+1])}
> >}
> >
> >  
> >
> >>VECTOR
> >>    
> >>
> > [1] 3 2 4 5 5 3 3 5 1 6 6
> >  
> >
> >>NEWVECTOR
> >>    
> >>
> >[1] 3 2 4 5 3 5 1 6
> >
> >_______________________________
> >Atte Tenkanen
> >University of Turku, Finland
> >
> >______________________________________________
> >R-help at stat.math.ethz.ch 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.
> >
> >
> >  
> >

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