R help - Feb 2008 - 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

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
>
> ______________________________________________
> 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.
> 

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

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?

Thompson, David (MNR) 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.
With:

 > move
[1] "b" "d" "h"

  you can do:

 > xxx[,c(match(move,names(xxx)),(1:dim(xxx)[2])[-match(move,names(xxx))])]

    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

  It basically uses match() to convert names to column numbers. You cant 
mix positive and negative indices so you need to take the matches you've 
got away from the 1:dim(xxx)[2] and that gives you the leftover column 
numbers.

  Don't forget to add a comment.

Barry