[R] Columnwise Alternate Subsetting of a Data Frame

[Moshe Olshansky]

You could do something like:

k <- dim(repo.dat)[2]
odd <- seq(from=1,to=k,by=2)
even <- seq(from=2,to=k,by=2)
even<-c(1,even)
df1 <- repo.dat[,odd)
colnames(df1) <- paste("V",odd,sep="")
df2 <- repo.dat[,even)
colnames(df2) <- paste("V",even,sep="")


--- On Mon, 23/6/08, Gundala Viswanath <gundalav at gmail.com> wrote:

> From: Gundala Viswanath <gundalav at gmail.com>
> Subject: [R] Columnwise Alternate Subsetting of a Data Frame
> To: r-help at stat.math.ethz.ch
> Received: Monday, 23 June, 2008, 1:03 PM
> Hi,
> 
> Given this data frame:
> 
> > print(repo.dat)
>                                V1             V2      V3   
>   V4
>       V5   .... (can be more)
> 1      1007_s_at   DDR1  2865.1  2901.3  1978.3   300.2
> 2       1053_at      RFC2   103.6    81.6   108.0         
> 101.3
> 
> I want to split them into two data frames yielding:
> 
>                                V1             V2         V3
>      ... etc
> 1      1007_s_at   DDR1  2865.1    1978.3
> 2       1053_at      RFC2   103.6      108.0
> 
> (V2 and V3 is obtain from V2 and V4 of original repo.dat)
> 
> and
> 
>                                V1                V2        
>   V3   ...etc
> 1      1007_s_at   DDR1    2901.3     300.2
> 2       1053_at      RFC2      81.6        101.3
> 
> 
> (V2 and V3 is obtain from V3 and V5 of original repo.dat)
> 
> In principle what we desire to do is to:
> 1. Given original data frame with V1, V2, V3, V4....
> 2. Split the data frame into two based on V2,V4,V6 ...
> (even) and V3,
> V5, V7 ..(odd) in the original data frame
> 3. Meanwhile keep row names and V1 in two newly formed data
> frames.
> 
> Is there a compact way to do it?
> 
> - Gundala Viswanath
> Jakarta - Indonesia
> 
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