Hi, Question to the GenomicRanges maintainer: In the GenomicRanges Use Cases manual, page 9, 7th line from the top of the page is the R line: >toTable(org.Sc.sgdGENENAME[systNames]) I found that the following line worked. >toTable(org.Sc.sgdGENENAME)[systNames,] Is that correct? If so please amend it in the manual. P. Kibet Korir Bioinformatics PhD Student, NUI Galway +353 86 224 19 66 [[alternative HTML version deleted]]

Hi Paul, So the code you list from the manual should actually be perfectly fine. You really can subset (single bracket) an AnnDbBimap object by name like this. Here is a concrete example: library(org.Sc.sgd.db) ## grab some arbitrary keys just to do an example systNames <- head(mappedLkeys(org.Sc.sgdCHRLOCEND)) ## then subset toTable(org.Sc.sgdGENENAME[systNames]) And in fact, you really want to do it that way when possible because it will be more efficient than the approach that you have proposed. In your 1st example below the manual showed how to subset the AnnDbBimap object itself which means that it does not have to retrieve *everything* for this mapping from the underlying database: only the stuff that you list in "systNames". IOW, the subset on the AnnDbBimap defines a narrower DB query that only gets made into a small data.frame when you subsequently call toTable() on it. But in the 2nd example you pull the entire thing into memory right at the start as a big gigantic data.frame using toTable(), and then you pare that down to the size you actually want. That is kind of a waste of memory. For most things it won't be an issue, but for some of the GO mappings you might start to really care. Also, unless your systNames are actually integers (which will be interpreted as indices and NOT as names), for the 2nd example to actually work I expect that you will have to do something more like this: toTable(org.Sc.sgdGENENAME)[systNames %in% listOfAllNamesInTheFrameProducedBytoTable,] So that way of doing things not only involves more processing, but more typing as well. Does this clarify things? Marc On 04/13/2011 04:09 AM, KORIR, PAUL wrote: > Hi, > > Question to the GenomicRanges maintainer: > > In the GenomicRanges Use Cases manual, page 9, 7th line from the top of the page is the R line: >> toTable(org.Sc.sgdGENENAME[systNames]) > I found that the following line worked. >> toTable(org.Sc.sgdGENENAME)[systNames,] > Is that correct? If so please amend it in the manual. > > P. Kibet Korir > Bioinformatics PhD Student, > NUI Galway > +353 86 224 19 66 > > [[alternative HTML version deleted]] > > _______________________________________________ > Bioconductor mailing list > Bioconductor at r-project.org > https://stat.ethz.ch/mailman/listinfo/bioconductor > Search the archives: http://news.gmane.org/gmane.science.biology.informatics.conductor