R help - Nov 2011 - Removing rows in dataframe w'o duplicated values

Hi,

Is there an easy way to remove dataframe rows without duplicated values of
a specified column ('id')?  e.g.,

dat <- data.frame(id = c(1,1,1,2,3,3), value = c(5,6,7,4,5,4), value2
c(1,4,3,3,4,3))
dat

  id value value2
1  1     5      1
2  1     6      4
3  1     7      3
4  2     4      3
5  3     5      4
6  3     4      3


This is sample data and the real data has hundreds of rows. In this
case, only row 4 does not have a duplicated id and I would like to
remove it without using:


dat$id[4] <- NULL


Any help is appreciated!


AC

	[[alternative HTML version deleted]]

This is ugly, but it gets what you want. 

dat[which(dat[,1] %in% unique((dat[duplicated(dat[,1], fromLast = T),
1]))),]






AC Del Re wrote
> 
> Hi,
> 
> Is there an easy way to remove dataframe rows without duplicated values of
> a specified column ('id')?  e.g.,
> 
> dat <- data.frame(id = c(1,1,1,2,3,3), value = c(5,6,7,4,5,4), value2
> c(1,4,3,3,4,3))
> dat
> 
>   id value value2
> 1  1     5      1
> 2  1     6      4
> 3  1     7      3
> 4  2     4      3
> 5  3     5      4
> 6  3     4      3
> 
> 
> This is sample data and the real data has hundreds of rows. In this
> case, only row 4 does not have a duplicated id and I would like to
> remove it without using:
> 
> 
> dat$id[4] <- NULL
> 
> 
> Any help is appreciated!
> 
> 
> AC
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help@ 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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Hi:

Here's one way:

do.call(rbind, lapply(L, function(d) if(nrow(d) > 1) return(d)))
    id value value2
1.1  1     5      1
1.2  1     6      4
1.3  1     7      3
3.5  3     5      4
3.6  3     4      3

HTH,
Dennis

On Tue, Nov 22, 2011 at 9:43 AM, AC Del Re <delre at wisc.edu>
wrote:
> Hi,
>
> Is there an easy way to remove dataframe rows without duplicated values of
> a specified column ('id')? ?e.g.,
>
> dat <- data.frame(id = c(1,1,1,2,3,3), value = c(5,6,7,4,5,4), value2
> c(1,4,3,3,4,3))
> dat
>
> ?id value value2
> 1 ?1 ? ? 5 ? ? ?1
> 2 ?1 ? ? 6 ? ? ?4
> 3 ?1 ? ? 7 ? ? ?3
> 4 ?2 ? ? 4 ? ? ?3
> 5 ?3 ? ? 5 ? ? ?4
> 6 ?3 ? ? 4 ? ? ?3
>
>
> This is sample data and the real data has hundreds of rows. In this
> case, only row 4 does not have a duplicated id and I would like to
> remove it without using:
>
>
> dat$id[4] <- NULL
>
>
> Any help is appreciated!
>
>
> AC
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> 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.
>

one approach is the following:

dat <- data.frame(id = c(1,1,1,2,3,3), value = c(5,6,7,4,5,4),
     value2 = c(1,4,3,3,4,3))

ind <- ave(dat$id, dat$id, FUN = length) > 1
dat[ind, ]


I hope it helps.

Best,
Dimitris


On 11/22/2011 6:43 PM, AC Del Re wrote:
> Hi,
>
> Is there an easy way to remove dataframe rows without duplicated values of
> a specified column ('id')?  e.g.,
>
> dat<- data.frame(id = c(1,1,1,2,3,3), value = c(5,6,7,4,5,4), value2
> c(1,4,3,3,4,3))
> dat
>
>    id value value2
> 1  1     5      1
> 2  1     6      4
> 3  1     7      3
> 4  2     4      3
> 5  3     5      4
> 6  3     4      3
>
>
> This is sample data and the real data has hundreds of rows. In this
> case, only row 4 does not have a duplicated id and I would like to
> remove it without using:
>
>
> dat$id[4]<- NULL
>
>
> Any help is appreciated!
>
>
> AC
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> 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.
>
-- 
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
Web: http://www.erasmusmc.nl/biostatistiek/

On Nov 22, 2011, at 12:43 PM, AC Del Re wrote:
> Hi,
>
> Is there an easy way to remove dataframe rows without duplicated  
> values of
> a specified column ('id')?  e.g.,
>
> dat <- data.frame(id = c(1,1,1,2,3,3), value = c(5,6,7,4,5,4),  
> value2 > c(1,4,3,3,4,3))
> dat
>
>  id value value2
> 1  1     5      1
> 2  1     6      4
> 3  1     7      3
> 4  2     4      3
> 5  3     5      4
> 6  3     4      3
 > dat[ave(dat$id, dat$id, FUN=length) >1, ]
   id value value2
1  1     5      1
2  1     6      4
3  1     7      3
5  3     5      4
6  3     4      3

>
>
> This is sample data and the real data has hundreds of rows. In this
> case, only row 4 does not have a duplicated id and I would like to
> remove it without using:
>
>
> dat$id[4] <- NULL
>
>
> Any help is appreciated!
>
>
> AC
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> 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.
David Winsemius, MD
West Hartford, CT