[Bioc-devel] request: high-level seqlevel utilities

[Julian Gehring]

Hi,

With the convenience that seqnamesStyles offers now, having to specify 
the chromosome name notation manually would feel like a step back.  In 
terms of subsetting genomic ranges, I normally think of four major 
groups of interest:

- Toplevel/standard: 1,..22,X,Y,MT
- Autosomes: 1,..,22
- Allosomes: X,Y
- "Linear": 1,..,22,X,Y

If you are concerned about confusing the user with many specialized 
functions, how about extending 'keepSeqlevels' by adding a e.g. 'group' 
argument that allows you to select a group of chromosomes as above.  As 
an example, think of:

## subset as before by seqname
keepSeqlevels(gr, "1")
keepSeqlevels(gr, value = "1")

## the new feature
keepSeqlevels(gr, group = "autosomes")

which would dispatch to specialized methods like '.keepAutosomes' in 
combination with 'seqnames.db'.  This way, one could also create a 
setting in which the groups can be easily extended by the user or other 
packages, by simply defining more of the specialized functions.

Best wishes
Julian