[BioC] GRanges - reduce() function

[Martin Morgan]

On 11/17/2011 05:57 PM, Jason Ross wrote:
> Hi Fahim,
>
> I am also frustrated by this. The meta-data also vanishes when using
> findOverlaps(). I'm thinking of writing some wrapper functions to place the
> meta-data back into the Granges object.

Hi Jason et al.,

The problem in 'reduce' is that the elementMetadata columns need to be 
'reduce'd too, and there is no universal way to do that -- for 
'transcripts' in Fahim's example, maybe it's just collapsing entries 
into a CharacterList, whereas for "Gene" it's split-by-reduced-range and 
'unique'. For numeric values one might sum or mean or max or ....

Can you be more specific about findOverlaps? It's not really clear which 
data you'd like to have propagated.

For Fahim's question, I arrived at

values(r)[["Gene"]] <-
     tapply(values(gr)[["Gene"]], match(gr, r), unique)

which I think is quite robust, but I'd recommend checking carefully on 
complicated data.

Martin

>
> Regards,
> Jason.
>
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