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Old 02-04-2013, 04:38 AM   #1
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Default splitting fastq?

I wonder if anyone knows about tools that allow splitting large fastq into smaller chunks. I found a couple scripts that split fasta, but not fastq.
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Old 02-04-2013, 04:52 AM   #2
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You can use "split" with the -l option (if your sequences/quality values do not wrap around on multiple lines). Check the manual page for split for more details.
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Old 02-04-2013, 04:55 AM   #3
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in unix use:

wc -l filename ### gets the number of lines

Then calculate how many lines you want in each smaller chunk to generate clean divisions of the data


split -l {number of lines to split} filename
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Old 02-04-2013, 05:43 AM   #4

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I also asked the same question before

Last edited by lorendarith; 02-04-2013 at 05:51 AM.
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Old 02-05-2013, 05:33 AM   #5
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Make sure you use numbers that are divisible by 4.
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Old 02-05-2013, 07:12 PM   #6
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If you aren't using Unix, you can get Unix tools by installing Cygwin.
Like people said, fastq is just a text file, anything that can split a text file will split a fastq file.
sed is generally slower than split, but you could try it:
sed -n 'start,endp' infile > outfile
the "p" after "end" means print, the "-n" means only print the selected lines, if you leave it out the original file is copied over and the selected lines appended to it (so don't leave it out).
e.g. you want a file with a million lines starting from the 4 millionth line:
sed -n '4000000,5000000p' infile > outfile

Last edited by Jeremy; 02-05-2013 at 10:31 PM.
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