R help - Sep 2008 - How to order some of my columns (not rows) alphabetically

Hello,

I have a dataframe with 9 columns, and I would like to sort (order) the 
right-most eight of them alphabetiaclly, i.e.:

ID1 ID2 F G A B C E D

would become

ID1 ID2 A B C D E F G

Right now, I'm using this code:

attach(data)
data<-data.frame(ID1,ID2,data[,sort(colnames(data)[3:9])])
detach(data)

but that's not very elegant. Ideally I could specify which columns to 
sort and which to leave "as is" (but my attempts to do so have
failed).

Thank you,

Mark

On Thu, 25 Sep 2008, Mark Na wrote:
> Hello,
>
> I have a dataframe with 9 columns, and I would like to sort (order) the 
> right-most eight of them alphabetiaclly, i.e.:
>
> ID1 ID2 F G A B C E D
>
> would become
>
> ID1 ID2 A B C D E F G
>
> Right now, I'm using this code:
>
> attach(data)
> data<-data.frame(ID1,ID2,data[,sort(colnames(data)[3:9])])
> detach(data)
>
> but that's not very elegant. Ideally I could specify which columns to
sort
> and which to leave "as is" (but my attempts to do so have
failed).
>
> Thank you,
>
> Mark
>
How about:
> df <- data.frame(z=1:2,a=3:4,y=5:6)
> df
   z a y
1 1 3 5
2 2 4 6
> sortdf <- df[,sort(names(df))]
> sortdf
   a y z
1 3 5 1
2 4 6 2

David Scott

_________________________________________________________________
David Scott	Department of Statistics, Tamaki Campus
 		The University of Auckland, PB 92019
 		Auckland 1142,    NEW ZEALAND
Phone: +64 9 373 7599 ext 86830		Fax: +64 9 373 7000
Email:	d.scott at auckland.ac.nz

Graduate Officer, Department of Statistics
Director of Consulting, Department of Statistics

On Thu, 25 Sep 2008, Mark Na wrote:
> Hello,
>
> I have a dataframe with 9 columns, and I would like to sort (order) the 
> right-most eight of them alphabetiaclly, i.e.:
>
> ID1 ID2 F G A B C E D
>
> would become
>
> ID1 ID2 A B C D E F G
>
> Right now, I'm using this code:
>
> attach(data)
> data<-data.frame(ID1,ID2,data[,sort(colnames(data)[3:9])])
> detach(data)
>
> but that's not very elegant. Ideally I could specify which columns to
sort
> and which to leave "as is" (but my attempts to do so have
failed).
>
> Thank you,
>
> Mark
>
OK, my first response was a bit quick and ignored the need to keep the 
first two columns.

The major point is that you can avoid the attach/detach if you use names 
in the subsetting:
> df <- data.frame(k1=1:2,k2=3:4,z=5:6,a=7:8,y=9:10)
> df
   k1 k2 z a  y
1  1  3 5 7  9
2  2  4 6 8 10
> sortdf <- df[,c(names(df)[1:2],sort(names(df)[3:5]))]
> sortdf
   k1 k2 a  y z
1  1  3 7  9 5
2  2  4 8 10 6

The rearrangement of the columns is just a one-liner and (in my view at 
least) easy to read and understand

David Scott

_________________________________________________________________
David Scott	Department of Statistics, Tamaki Campus
 		The University of Auckland, PB 92019
 		Auckland 1142,    NEW ZEALAND
Phone: +64 9 373 7599 ext 86830		Fax: +64 9 373 7000
Email:	d.scott at auckland.ac.nz

Graduate Officer, Department of Statistics
Director of Consulting, Department of Statistics