[BioC] Rsubread/Rsamtools mappings outside of chromosome ranges
Wei Shi
shi at wehi.EDU.AU
Tue Feb 14 23:36:53 CET 2012
Hi Thomas,
After re-checking the changes we have made before for addressing the issue of reads mapped out of the chromosome ranges, I found we actually made the decision to allow reads to be mapped out of the chromosome ranges, due to the fact that the reference sequences might not be complete and reads could originate from outside of the reference sequences used for mapping.
So you may take Martin's suggestion to add extra parameters when you call 'readGappedAlignments' function to make it work for you. Or alternatively you may try the 'featureCounts' function in Rsubread package to count the number of reads mapped to each gene, if the purpose of your analysis is perform RNA-seq analysis. This function works on SAM file, so you do not need to convert it to a BAM file. But you will have to provide an Arabidopsis anntation file it as it has built-in annotation for mouse and human only at present.
I think it might be better if the 'readGappedAlignments' function could allow reads being mapped outside of chromosomal ranges. We have been successfully running through a SNP discovery pipeline using subread/subjunc, samtools and vcftools on unix command lines, which does not complain about the reads mapped outside of the chromosomal ranges. I guess many other downstream analysis tools do not require mapping locations of reads to be within the chromosomal ranges as well.
Hope this helps.
Cheers,
Wei
On Feb 14, 2012, at 11:58 AM, Thomas Girke wrote:
> That's great, thanks a lot!
>
> BTW: are there any published/shareable performance test results
> available comparing subread against other RNA-read to genome aligners
> such as Tophat with respect to the accuracy of aligning reads across
> exon/intron junctions?
>
> Thanks,
>
> Thomas
>
> On Mon, Feb 13, 2012 at 11:41:42PM +0000, Wei Shi wrote:
>> Hi Thomas,
>>
>> I have just committed changes to both the release version and the devel version of Rsubread package to fix the bug of mapping reads out of chromosomal boundaries. They should be available in 24-36 hours. Please rebuild your index when you rerun your alignment.
>>
>> Let me know if the problem persists or you encounter further problems.
>>
>> Cheers,
>> Wei
>>
>> On Feb 13, 2012, at 11:12 AM, Thomas Girke wrote:
>>
>>> Thanks Martin for your suggestion!
>>>
>>> Thomas
>>>
>>> On Sun, Feb 12, 2012 at 05:28:21PM +0000, Martin Morgan wrote:
>>>> On 02/10/2012 07:44 PM, Thomas Girke wrote:
>>>>> With some Illumina libraries I have been running into problems importing
>>>>> the read mappings from Rsubread into Rsamtools. After some testing I
>>>>> found out that some reads reported in Rsubread's SAM output have their
>>>>> end positions outside of the chromosome ranges. If those reads are
>>>>> removed from the SAM file then the import into Rsamtools works just
>>>>> fine. Below is a reproducible example of this problem.
>>>>>
>>>>> I could think of several solutions to fix this, e.g. not reporting reads
>>>>> outside of chromosome ranges or updating their length in the CIAGR string.
>>>>> An additional option could be to remove invalid mappings during the import
>>>>> into Rsamtools.
>>>>
>>>> Hi Thomas --
>>>>
>>>> for the latter and for the case where those reads are intrinsically not
>>>> interesting, it might be reasonable to specify a range on
>>>> readGappedAlignments that precludes the possibility of extension beyond
>>>> sequence ends.
>>>>
>>>>> si <- seqinfo(BamFile(fl))
>>>>> gr <- GRanges(seqnames(si), IRanges(34, seqlengths(si)-34))
>>>>> bam <- readGappedAlignments(fl, param=ScanBamParam(which=gr))
>>>>
>>>> One would like a better solution, either doing this automatically with a
>>>> warning, or warning rather than stopping on reads overlapping ends.
>>>>
>>>> Martin
>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Thomas
>>>>>
>>>>> ################################
>>>>> ## Read mapping with Rsubread ##
>>>>> ################################
>>>>> library(Rsubread)
>>>>> ## Reference source: ftp://ftp.arabidopsis.org/home/tair/Sequences/whole_chromosomes/
>>>>> ## Fastq source: ftp://ftp-trace.ncbi.nih.gov/sra/sra-instant/reads/ByStudy/sra/SRP%2FSRP009%2FSRP009850/SRR390302/
>>>>> buildindex(basename="tair10chr.fasta", reference="tair10chr.fasta")
>>>>> align(index="tair10chr.fasta", readfile1="SRR390302.fastq", output_file="SRR390302_subread.sam", nthreads=8, indels=1, TH1=2)
>>>>>
>>>>> #####################################
>>>>> ## Process SAM file with Rsamtools ##
>>>>> #####################################
>>>>> library(Rsamtools)
>>>>> asBam(file="SRR390302_subread.sam", destination="SRR390302_subread")
>>>>> [1] "./data/SRR390302_subread.bam"
>>>>> reads<- readBamGappedAlignments("SRR390302_subread.bam", use.names=FALSE)
>>>>> Error in validObject(.Object) :
>>>>> invalid class "GappedAlignments" object: 'ranges' contains values outside of sequence bounds
>>>>>
>>>>> ## The error disappears if the following two reads are removed from the SAM file:
>>>>> ## SRR390302.434558 and SRR390302.2716043. Both reads have their end positions outside
>>>>> ## the range of Chr5 as illustrated here:
>>>>>
>>>>> ## Relevant chunks of SAM file generated by Rsubread
>>>>> @SQ SN:Chr1 LN:30427671
>>>>> @SQ SN:Chr2 LN:19698289
>>>>> @SQ SN:Chr3 LN:23459830
>>>>> @SQ SN:Chr4 LN:18585056
>>>>> @SQ SN:Chr5 LN:26975502
>>>>> @SQ SN:ChrC LN:154478
>>>>> @SQ SN:ChrM LN:366924
>>>>> SRR390302.1 0 Chr1 27018257 2.0 35M * 0 0 TGG...ACC III...GD)0
>>>>> SRR390302.2 4 * 0 0 * * 0 0 TCC...AAA III...+I@
>>>>> ...
>>>>> SRR390302.434558 0 Chr5 26975485 5.0 35M * 0 0 ATG...TGG III...&4(
>>>>> SRR390302.2716043 0 Chr5 26975486 3.0 35M * 0 0 CAT...GGT III...+2&
>>>>>
>>>>>
>>>>>> sessionInfo()
>>>>> R version 2.14.0 (2011-10-31)
>>>>> Platform: x86_64-unknown-linux-gnu (64-bit)
>>>>>
>>>>> locale:
>>>>> [1] C
>>>>>
>>>>> attached base packages:
>>>>> [1] stats graphics grDevices utils datasets methods base
>>>>>
>>>>> other attached packages:
>>>>> [1] Rsamtools_1.6.3 Biostrings_2.22.0 GenomicRanges_1.6.4 IRanges_1.12.5 Rsubread_1.4.2
>>>>>
>>>>> loaded via a namespace (and not attached):
>>>>> [1] BSgenome_1.22.0 RCurl_1.8-0 XML_3.6-2 bitops_1.0-4.1 rtracklayer_1.14.4 tools_2.14.0 zlibbioc_1.0.0
>>>>>
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>>>>
>>>>
>>>> --
>>>> Computational Biology
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>>>>
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