Hello,

I agree, what you say fits perfectly for GATK, but as I wanted to create a
more generic code I did it this way (also because I am a newbie in the
galaxy code and I didn't know so well how to implement this ). What about a
tool that doesn't accept a region, just a bam? Maybe we can put another
parameter in the parallelism tag that force to split the bam.
Mostly, just to create a bed file would be better, right?
What do you think?

Regards

On 6 May 2015 at 12:23, Peter Cock <p.j.a.c...@googlemail.com> wrote:

> Hi Roberto,
>
> Given the way BAM indexing works, I see no reason to actually
> split the BAM file at all - it seems like wasted disk IO.
>
> Instead, can you split a BED file into sub-regions? This way
> each child GATK job would look at the full BAM file but only for
> a small region described in the split BED region file?
>
> Peter
>
>
> On Wed, May 6, 2015 at 11:19 AM, Roberto Alonso CIPF <ralo...@cipf.es>
> wrote:
> > Hello,
> >
> > I have been working in the Galaxy parallelization module and I would
> like to
> > ask you some questions that I have about how to face one problem.
> > I have done one pull request about splitting bams:
> > https://github.com/galaxyproject/galaxy/pull/184
> >
> > Regarding this, I think it is useful but it could be more while accessing
> > somehow the interval. I better explain it with an example:
> > If I define a simple tool like this, with the parallelism tag "actived":
> >
> > <tool id="gatk" name="call with gatk">
> >   <description>gatk</description>
> >   <parallelism method="multi" split_mode="by_interval"
> > split_size="100000000" merge_outputs="output" split_inputs="input"
> >></parallelism>
> >
> >   <command>
> > ## by_rname
> > ln -s $input input.bam;
> > samtools index input.bam;
> > UnifiedGenotyper -R /home/ralonso/BiB/Galaxy/data/hg19_ucsc.fa -I
> input.bam
> > -o $output -L REGION ;
> >
> >   </command>
> >   <inputs>
> >     <param format="bam" name="input" type="data" label="bam"/>
> >   </inputs>
> >   <outputs>
> >       <data format="vcf" name="output" />
> >   </outputs>
> >
> >   <help>
> >   bwa
> >   </help>
> > </tool>
> >
> > The region is based on the field split_size, it is better explained in
> the
> > PR.
> > How does the code from the PR work? It goes through the bam file and does
> > something like "samtools view REGION -o bam_splitted.bam", so then GATK
> does
> > the calling for this small bam, but what is the problem? As you know, in
> the
> > software GATK if you don't pass the region as an argument in the command
> > line it goes through all the genome, so it is very slow. So, what would
> you
> > recommend to me to be able to pass this information to GATK? I was
> thinking
> > to create, at the same time the bam is splitted, a file region.bed and
> use
> > it in the tool definition xml, so the command would be like this:
> >   <command>
> > ...
> > UnifiedGenotyper -R /home/ralonso/BiB/Galaxy/data/hg19_ucsc.fa -I
> input.bam
> > -o $output -L region.bed;
> > </command>
> >
> > This solution does not convince me too much because it is a bit
> intrusive in
> > the tool definition and also because you have to trust that the
> region.bed
> > file exists.
> > Do you have any opinion, suggestion...?
> >
> > Thanks a lot!
> >
> > Best regards
> >
> >
> > --
> > Roberto Alonso
> > Functional Genomics Unit
> > Bioinformatics and Genomics Department
> > Prince Felipe Research Center (CIPF)
> > C./Eduardo Primo Yúfera (Científic), nº 3
> > (junto Oceanografico)
> > 46012 Valencia, Spain
> > Tel: +34 963289680 Ext. 1021
> > Fax: +34 963289574
> > E-Mail: ralo...@cipf.es
> >
> > ___________________________________________________________
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>



-- 
Roberto Alonso
Functional Genomics Unit
Bioinformatics and Genomics Department
Prince Felipe Research Center (CIPF)
C./Eduardo Primo Yúfera (Científic), nº 3
(junto Oceanografico)
46012 Valencia, Spain
Tel: +34 963289680 Ext. 1021
Fax: +34 963289574
E-Mail: ralo...@cipf.es
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