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

From: jim holtman <jholtman_at_gmail.com>
Date: Tue, 12 Feb 2008 12:41:27 -0500

try this:

> x <- read.table(textConnection(" 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"), header=TRUE)

> # initial columns
> init.cols <- c('b', 'd', 'h')
> # now get the remaining
> remaining <- setdiff(colnames(x), init.cols)
> x[,c(init.cols, remaining)]

   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
>

On Feb 12, 2008 12:19 PM, Thompson, David (MNR) <David.John.Thompson_at_ontario.ca> wrote:
> 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
>
> ______________________________________________
> 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.
>

-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?

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Received on Tue 12 Feb 2008 - 17:45:51 GMT

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