[R] How to get row numbers of a subset of rows
Julian Burgos
jmburgos at u.washington.edu
Wed Nov 14 20:38:20 CET 2007
One way to do this is
range(which(B[,2]==1))
Julian
affy snp wrote:
> Hello list,
>
> I read in a txt file using
>
> <B<-read.table(file="data.snp",header=TRUE,row.names=NULL)
>
> by specifying the row.names=NULL so that the rows are numbered.
> Below is an example after how the table looks like using
> <B[1:10,1:3]
>
>
> SNP Chromosome PhysicalPosition
> 1 SNP_A-1909444 1 7924293
> 2 SNP_A-2237149 1 8173763
> 3 SNP_A-4303947 1 8191853
> 4 SNP_A-2236359 1 8323433
> 5 SNP_A-2205441 1 8393263
> 6 SNP_A-1909445 1 7924293
> 7 SNP_A-2237146 2 8173763
> 8 SNP_A-4303946 2 8191853
> 9 SNP_A-2236357 2 8323433
> 10 SNP_A-2205442 2 8393263
>
> I am wondering if there is a way to return the start and end row numbers
> for a subset of rows.
>
> For example, If I specify B[,2]=1, I would like to get
> start=1 and end=6
>
> if B[,2]=2, then start=7 and end=10
>
> Is there any way in R to quickly do this?
>
> Thanks a bunch!
>
> Allen
>
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