[R] Reorder data frame columns by negating list of names

[Dimitris Rizopoulos]

one way is the following:

xxx <- data.frame(matrix(1:40, ncol=8))
names(xxx) <- letters[1:8]

ind <- c('b', 'd', 'h')
nams <- names(xxx)
xxx[c(ind, nams[!nams %in% 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: "Thompson, David (MNR)" <David.John.Thompson at ontario.ca>
To: <r-help at r-project.org>
Sent: Tuesday, February 12, 2008 6:19 PM
Subject: [R] Reorder data frame columns by negating list of names


> Hello,
>
> I would like to reorder columns in a data frame by their names as
> demonstrated below:
>
> Take this data frame:
> > xxx <- data.frame(matrix(1:40, ncol=8))
> > names(xxx) <- letters[1:8]
> > xxx
>   a  b  c  d  e  f  g  h
> 1 1  6 11 16 21 26 31 36
> 2 2  7 12 17 22 27 32 37
> 3 3  8 13 18 23 28 33 38
> 4 4  9 14 19 24 29 34 39
> 5 5 10 15 20 25 30 35 40
>
> and reorder the columns like this:
> > xxx[,c( c('b', 'd', 'h'), c('a', 'c', 'e', 'f', 'g') )]
>    b  d  h a  c  e  f  g
> 1  6 16 36 1 11 21 26 31
> 2  7 17 37 2 12 22 27 32
> 3  8 18 38 3 13 23 28 33
> 4  9 19 39 4 14 24 29 34
> 5 10 20 40 5 15 25 30 35
>
> where I only have to name the columns that I'm interested in moving 
> to
> the first few positions, something like:
> > xxx[,c( c('b', 'd', 'h'), -c('b', 'd', 'h') )]
> Error in -c("b", "d", "h") : invalid argument to unary operator
>
> Suggestions? and Thank you, DaveT.
> *************************************
> Silviculture Data Analyst
> Ontario Forest Research Institute
> Ontario Ministry of Natural Resources
> david.john.thompson at ontario.ca
> http://ofri.mnr.gov.on.ca
>
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