Hi Martin.
My data is generated from the old pipeline (illumina 0.3) and therefore should
not be a problem. In any case I tested your suggestion but it had no effect on
the data. The colMeans(m) are the same before and after incorporating your
suggestions. Also when I use alignQuality I get NAs in both cases. Let me know
how I can help to trouble shoot this. -- Fuad
The first part is using my original data:
> aln
class: AlignedRead
length: 4933275 reads; width: 32 cycles
chromosome: phiX174 phiX174 ... phiX174 phiX174
position: 5147 1513 ... 5034 3107
strand: - - ... + +
alignQuality: NumericQuality
alignData varLabels: similar mismatch
> head(quality(aln))
class: SFastqQuality
quality:
A BStringSet instance of length 6
width seq
[1] 32 <<<<<<<<<<<<<<<<<;<<<;<<<<<5.<,:
[2] 32 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
[3] 32 <<<<<<<<<<<<;<<;<<<<<<<+<<<<<<<<
[4] 32 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
[5] 32 <<<<<<<<<<<<<<<<<<<;<<<<<<<<<<6<
[6] 32 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
> m <- as(quality(aln), "matrix")
> colMeans(m)
[1] -3.865733 -3.867642 -3.878435 -3.869599 -3.884619 -3.891333 -3.904493
[8] -3.933454 -3.965951 -3.995224 -4.301351 -4.331125 -4.427614 -4.495761
[15] -4.556334 -4.586264 -4.623881 -4.653223 -4.744307 -4.825347 -4.913756
[22] -5.000141 -5.138716 -5.213431 -5.375823 -5.635962 -5.779450 -5.791400
[29] -5.944196 -6.175808 -6.368913 -6.597291
> alignQuality(aln)
class: NumericQuality
quality: NA NA ... NA NA (4933275 total)
##################
incorporating your suggestions
##################
> qual <- FastqQuality(quality(quality(aln)))
> qual
class: FastqQuality
quality:
A BStringSet instance of length 4933275
width seq
[1] 32 <<<<<<<<<<<<<<<<<;<<<;<<<<<5.<,:
[2] 32 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
[3] 32 <<<<<<<<<<<<;<<;<<<<<<<+<<<<<<<<
[4] 32 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
[5] 32 <<<<<<<<<<<<<<<<<<<;<<<<<<<<<<6<
[6] 32 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
[7] 32 <<<<<<<<<<<<<<<<+<-<<<<;<<<<<<<<
[8] 32 <<<<<<<<<<<<<<<<<<<<<<<<<,<+<<<<
[9] 32 <<<<<<<<<<<<<<<<<<<5<<<<7<<<<<<2
... ... ...
[4933267] 32 <<<<<<<<<<<<<<<<<<<<<<3<<8<<<<<<
[4933268] 32 <<<<<<<<<<<<<<<<<<<<<;<<<98<<<<<
[4933269] 32 <<<<<<<<<<<<<<<<</<<<5<<1;<;<7<<
[4933270] 32 <<<<<<<<<<<<<<<<<<<<<<<<;<<<<<6:
[4933271] 32 <<<<<<<<73;<;<<<<<;';57<;<0;<<55
[4933272] 32 <<<<<<3<<<<<<<<6<<<<<<-7<<<7*<<7
[4933273] 32 <<<<<<<<<<<<<3<<<<<<+<<6<<<4&5<6
[4933274] 32 <<<<<<<<<<<<<<<<<<<<<<<<4<<<<<<<
[4933275] 32 <<<<<<<<<<<<<<<<<7<<;<8<<6<<<<<)
> initialize(aln, quality=qual)
class: AlignedRead
length: 4933275 reads; width: 32 cycles
chromosome: phiX174 phiX174 ... phiX174 phiX174
position: 5147 1513 ... 5034 3107
strand: - - ... + +
alignQuality: NumericQuality
alignData varLabels: similar mismatch
> m <- as(quality(aln), "matrix")
> colMeans(m)
[1] -3.865733 -3.867642 -3.878435 -3.869599 -3.884619 -3.891333 -3.904493
[8] -3.933454 -3.965951 -3.995224 -4.301351 -4.331125 -4.427614 -4.495761
[15] -4.556334 -4.586264 -4.623881 -4.653223 -4.744307 -4.825347 -4.913756
[22] -5.000141 -5.138716 -5.213431 -5.375823 -5.635962 -5.779450 -5.791400
[29] -5.944196 -6.175808 -6.368913 -6.597291
> alignQuality(aln)
class: NumericQuality
quality: NA NA ... NA NA (4933275 total)
> sessionInfo()
R version 2.9.1 (2009-06-26)
x86_64-unknown-linux-gnu
locale:
LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=C;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] ShortRead_1.3.22 lattice_0.17-25 BSgenome_1.13.10 Biostrings_2.13.29
[5] IRanges_1.3.44
loaded via a namespace (and not attached):
[1] Biobase_2.4.1 grid_2.9.1 hwriter_1.1
> Date: Tue, 4 Aug 2009 09:07:51 -0700
> From: [email protected]
> To: [email protected]
> CC: [email protected]; [email protected];
> [email protected]
> Subject: Re: [Bioc-sig-seq] Problem with ShortRead reading quality scores
> from bowtie
>
> Martin Morgan wrote:
> > Fuad Gwadry wrote:
> >> Hi All
> >>
> >>
> >>
> >> I am getting negative values when reading quality scores when I read
> >> data generated in bowtie. Has anyone run into the same issue when
> >> using data generated by bowtie ? My session info is below.
> >
> > Hi Fuad -- ShortRead is reading the quality scores on the wrong scale
> > (solexa, rather than phred; this will be fixed before the next release).
> > Try
> >
> > qual <- FastqQuality(quality(quality(aln))
> > initialize(aln, quality=qual)
> >
> > to update aln, or
> >
> > m <- as(FastqQuality(quality(quality(aln)), "matrix")
> >
> > for a one-off solution.
>
> I wanted to clarify, too, both for this post and one yesterday, that
> as() is simply converting the character encoding to the corresponding
> integer value that each letter encodes; there is a secondary mapping
> from this encoding to log-odds or phred score that is not being
> performed. This step is, I think
>
> 10^(-m/10) for phred scores
> 1 - 1 / (1 + 10^(-m/10)) for Solexa scores
>
> Solexa has changed its encoding scheme very recently; I think it is now
> standard phred but am not sure.
>
> Martin
>
> >
> > Martin
> >
> >>
> >>
> >>
> >> Thanks in advance
> >>
> >>
> >>
> >> Fuad
> >>
> >>
> >>
> >>> aln
> >> class: AlignedRead
> >> length: 4591807 reads; width: 32 cycles
> >> chromosome: chr13 chr7 ... chr6 chr4 position: 93437004 13223395 ...
> >> 23636747 23353864 strand: - - ... + + alignQuality: NumericQuality
> >> alignData varLabels: similar mismatch
> >>
> >>> m <- as(quality(aln), "matrix")
> >>> colMeans(m)
> >> [1] -7.186638 -7.205858 -7.203382 -7.197175 -7.203629 -7.217016
> >> [7] -7.240661 -7.249238 -7.268499 -7.286551 -7.306615 -7.324003
> >> [13] -7.523238 -7.581242 -7.697591 -7.695861 -7.735321 -7.743323
> >> [19] -7.752996 -7.849403 -7.862658 -7.931969 -7.979778 -8.029288
> >> [25] -8.120469 -8.215818 -8.335176 -8.411609 -8.587005 -8.820979
> >> [31] -11.447326 -11.644198
> >>
> >>
> >>> sessionInfo()
> >> R version 2.9.1 (2009-06-26) x86_64-unknown-linux-gnu
> >> locale:
> >> LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=C;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C
> >>
> >>
> >>
> >> attached base packages:
> >> [1] stats graphics grDevices utils datasets methods base
> >> other attached packages:
> >> [1] ShortRead_1.3.22 lattice_0.17-25 BSgenome_1.13.10
> >> Biostrings_2.13.29
> >> [5] IRanges_1.3.44
> >> loaded via a namespace (and not attached):
> >> [1] Biobase_2.4.1 grid_2.9.1 hwriter_1.1
> >>
> >> _________________________________________________________________
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> >>
> >> _______________________________________________
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> >> [email protected]
> >> https://stat.ethz.ch/mailman/listinfo/bioc-sig-sequencing
> >
> >
>
>
> --
> Martin Morgan
> Computational Biology / Fred Hutchinson Cancer Research Center
> 1100 Fairview Ave. N.
> PO Box 19024 Seattle, WA 98109
>
> Location: Arnold Building M1 B861
> Phone: (206) 667-2793
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