Blog Archives

Quality trimming in R using ShortRead and Biostrings

March 3, 2010
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I wrote an R function to do soft-trimming, right clipping FastQ reads based on quality.This function has the option of leaving out sequences trimmed to extinction and will do left-side fixed trimming as well.#softTrim#trim first position lower than minQuality and all subsequent positions#omit sequences that after trimming are shorter than minLength#left trim to firstBase, (1 implies no left trim)#input:...

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R’s xtabs for total weighted read coverage

November 4, 2009
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Samtools and its BioPerl wrapper Bio::DB:Sam prefer to give read coverage on a depth per base pair basis. This is typically an array of depths, one for every position that has at least one read aligned. OK, works for me. But how can we quickly see which targets (in my case transcripts) have the greatest total weighted read coverage...

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R’s xtabs for total weighted read coverage

November 4, 2009
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Samtools and its BioPerl wrapper Bio::DB:Sam prefer to give read coverage on a depth per base pair basis. This is typically an array of depths, one for every position that has at least one read aligned. OK, works for me. But how can we quickly see which targets (in my case transcripts) have the greatest total weighted read coverage...

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Standardized Velvet Assembly Report

August 25, 2009
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Standardized Velvet Assembly Report

http://code.google.com/p/standardized-velvet-assembly-report/I finally got my Velvet Assembler report script up on google code. This "program" consists of some short scripts and a Sweave report designed to help Velvet users identify the optimal kmer an...

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Standardized Velvet Assembly Report

August 25, 2009
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Standardized Velvet Assembly Report

http://code.google.com/p/standardized-velvet-assembly-report/I finally got my Velvet Assembler report script up on google code. This "program" consists of some short scripts and a Sweave report designed to help Velvet users identify the optimal kmer an...

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Calculating an N50 from Velvet output

November 25, 2008
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In sequencing circles the N50 length is a useful heuristic for judging the quality of an assembly. Here is my definition of N50 length, which you may or may not find intuitive: N50 length is the length of the shortest contig such that the sum of contigs of equal length or longer is at least 50% of the total length...

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Calculating an N50 from Velvet output

November 25, 2008
By

In sequencing circles the N50 length is a useful heuristic for judging the quality of an assembly. Here is my definition of N50 length, which you may or may not find intuitive:N50 length is the length of the shortest contig such that the sum of contigs of equal length or longer is at least 50% of the total length...

Read more »