qrqc and all supporting documentation Copyright (c) Vince Buffalo, 2011-2012
Contact: Vince Buffalo vsbuffaloAAAAA@gmail.com (with the poly-A tail removed)
If you wish to report a bug, please open an issue on Github (http://github.com/vsbuffalo/qrqc/issues) or post it on the Bioconductor support site (https://support.bioconductor.org/). You can contact me personally as well, but please open an issue first.
qrqc (short for "Quick Read Quality Control") is a fast and extensible package that reports basic quality and summary statistics on FASTQ and FASTA files, including base and quality distribution by position, sequence length distribution, and common sequences.
GNU General Public License, version 2.
ggplot2
?I've had some feature requests for qrqc
since its release, mostly
related to customizing the graphics. Since data accessibility and
custom graphics were the reason I created qrqc
, I initially rewrote
qrqc
to provide more graphics options through lattice
. However,
all the graphics parameters I added led to large numbers of arguments
to functions and high complexity. This rewrite uses ggplot2
, which
is a very excellent way to create graphics as any graphics object can
be further manipulated.
qrqc
is fast because it bins the quality scores of bases by
positions; there is data summarization done by readSeqFile
. To
create a smooth curve, the function needs multiple data points (not
binned data), which I simulate via Monte Carlo draws from the quality
distribution by position. This is an approximation, but it leads to a
smooth curve which can create a useful visual tool in assessing
quality drops.
Illumina reads often have poor 3'-end qualities. I've noticed that
HiSeq machines also produce poor quality 5'-ends. For increased
mapping rates and better assmeblies, it is generally advisable that
these poor quality regions be trimmed off. Nik Joshi's took sickle
tool can do this; you can get it here
http://github.com/najoshi/sickle.
3'-end adapter contamination can be difficult to recognize (and thus
remove) due to poor quality and likely incorrect bases. I've developed
a tool called scythe
that removes
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