Sorry, this is due to my lack of knowledge of R I suspect! I have an MAList object in limma containing several arrays. I access the column of M values thus: MAn[,3]$M Where Man is my MAList object. What I want to do is create a factor which tells me which entries of that M column are NA and which aren't - I basically want to highlight on a background plot those spots which are going to produce a negative value after background subtraction, and therefore an NA value in the MAList object. Thanks in advance for the help Mick

Mick, I'm not sure what format you want your data to be in to accomplish your stated task, but you might need so see ?is.na and ?apply. Sean On Aug 13, 2004, at 5:11 AM, michael watson (IAH-C) wrote: > Sorry, this is due to my lack of knowledge of R I suspect! > > I have an MAList object in limma containing several arrays. I access > the column of M values thus: > > MAn[,3]$M > > Where Man is my MAList object. What I want to do is create a factor > which tells me which entries of that M column are NA and which aren't - > I basically want to highlight on a background plot those spots which > are > going to produce a negative value after background subtraction, and > therefore an NA value in the MAList object. > > Thanks in advance for the help > > Mick > > _______________________________________________ > Bioconductor mailing list > Bioconductor@stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/bioconductor