How to remove similar successive objects from a vector? - R-help

Wed, Aug 16, 2006 12:42 AM #

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])}
}

[1] 3 2 4 5 5 3 3 5 1 6 6

[1] 3 2 4 5 3 5 1 6

_______________________________
Atte Tenkanen
University of Turku, Finland

Dimitris Rizopoulos

Wed, Aug 16, 2006 12:57 AM #

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?

_______________________________
Atte Tenkanen
University of Turku, Finland

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Jacques VESLOT

Wed, Aug 16, 2006 1:01 AM #

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

-------------------------------------------------------------------
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Atte Tenkanen a ?crit :

_______________________________
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

Wed, Aug 16, 2006 1:05 AM #

On Wed, Aug 16, 2006 at 10:42:35AM +0300, Atte Tenkanen wrote:

How about rle? rle(VECTOR)$values should do the same thing. Don't know
about efficiency, though.

Jarimatti Valkonen

Gavin Simpson

Wed, Aug 16, 2006 1:05 AM #

On Wed, 2006-08-16 at 10:42 +0300, Atte Tenkanen wrote:

_______________________________
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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