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tophat 2 rna seq

hi all. i have a fastq file with total sequences 28020920 but i only want to do 10.000 f.e. . which option is there because i cant seem to find that in the manual.

rna-seq

Not sure why you want to do that but you could use reformat.sh from BBMap suite to sample the 10000 reads into a new file and then use that.

reformat.sh in=reads.fq.gz out=sampled.fq.gz sample=10000

thank you. but cant you do it using tophat?

You can check the manual but I don't think tophat has an option to sample a fraction of reads.

Hi dimitrischat,

It's worth noting that TopHat2 has been, essentially, deprecated by the developers, who recommend using HISAT2 instead. Unless you have a very specific reason to adopt TopHat2 in your pipeline, it's probably best to follow their advice.

1 answer

Hi Dimitris - I guess you want a small sample of your reads for testing and debugging purposes. If so, you can create a file containing a small number of reads. For example:

$ zcat myreads.fastq.gz | head -400000 | gzip > Test100k.fastq.gz

which takes the first 100k reads from “myreads” and stores them in “Test100k”

Hope it helps!

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