[R] How to get row numbers of a subset of rows

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] SNPChromosome PhysicalPosition 1

Re: [R] How to get row numbers of a subset of rows

Here is a way of doing it using 'rle': x - read.table(textConnection( SNPChromosome PhysicalPosition + 1 SNP_A-1909444 1 7924293 + 2 SNP_A-2237149 1 8173763 + 3 SNP_A-4303947 1 8191853 + 4 SNP_A-2236359 1

Re: [R] How to get row numbers of a subset of rows

Am I missing something? ... Why not: range(seq(nrow(B))[B[,2]==1] ) ?? ## note: == not = Alternatively, and easily generalized (to start with a frame which is a subset of the original and any subset of rows, contiguous or not) range(as.numeric(row.names(B)[B[,2]==1])) Again, am I missing

Re: [R] How to get row numbers of a subset of rows

That works for the specific value of '1', but you would have to repeat it for other values in the column. If you had 100 different ranges in that column, what would you do? Here is another solution using 'range' on the same data: tapply(seq_len(nrow(x)), x$Chromosome, range) $`1` [1] 1 6 $`2`

Re: [R] How to get row numbers of a subset of rows

Thanks a lot, Jim and Bert. It worked pretty well. Best, Allen On Nov 14, 2007 12:11 PM, jim holtman [EMAIL PROTECTED] wrote: That works for the specific value of '1', but you would have to repeat it for other values in the column. If you had 100 different ranges in that column, what

Re: [R] How to get row numbers of a subset of rows

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

Re: [R] How to get row numbers of a subset of rows

Thank you very much, Julian. I got it. Best, Allen On Nov 14, 2007 2:38 PM, Julian Burgos [EMAIL PROTECTED] wrote: One way to do this is range(which(B[,2]==1)) Julian affy snp wrote: Hello list, I read in a txt file using