On Mon, 11 Oct 2010, Steve Lianoglou wrote:

Hi Chuck,

On Mon, Oct 11, 2010 at 11:24 AM, Charles C. Berry <[email protected]> wrote:

We are liking the idioms that go with GenomicRanges and RangedData Objects
(follow, precede, findOverlaps, etc), but we are bumping up against memory
demands of loading very large objects.

Is there now or will there soon be a cached version of these that will
lessen our memory requirements?

If not, is there a cookbook as to how to create and save cached versions of
these objects.

Or maybe a place to look in the bioConductor codebase to get some ideas of
how to go about constructing cached versions of these classes?

I'm not sure what you mean by caching -- do you want them serialized
to disk and you read off parts when you need them, or?

That's basically the idea. I looked at how BSGenome handles FASTA, and it allows you to read in one chromosome, make apparent copies that do not physically copy the object unless it is modified, and then clean up afterwards without much of the work under the hood.



Also -- I typically split my data and processing to work on a
chromosome by chromosome basis -- even though the GenomicRanges
infrastructure allows you to keep ranges spanning multiple chromosomes
in one object. Although it's a bit more book keeping code on my part,
I find that doing so helps to keep my RAM requirements down a bit.
Perhaps that obvious/marginal suggestion might help for the time
being?

Thanks. We have bits and pieces of a pipeline that do that. But we are about to refactor that pipeline, so the hope is to make something that is fairly clean, will endure, and handle the large objects that new sequencing technologies are likely to throw at us.

Chuck

-steve

--
Steve Lianoglou
Graduate Student: Computational Systems Biology
 | Memorial Sloan-Kettering Cancer Center
 | Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact


Charles C. Berry                            (858) 534-2098
                                            Dept of Family/Preventive Medicine
E mailto:[email protected]               UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901

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