how to extract particular regions of a sequence from fasta file if its range for each sequence from fasta file is given in another txt file for all the sequences contains in fasta file ?

Hi folks, I have a fasta file ( 716_seq.fasta ) with 716 sequences I want a specific region which is different in all 716 sequences and I have the range in a different txt file (range.txt ) for each 716 sequence. I am able to do this for only for a single range for all the sequences by providing its range in code. I want it takes second range for second sequence and 3rd range for 3rd sequence, and so on. Please help.

716_seq.fasta file like this:

>header_seq1_>xyz
ATGACATGACGATC
ATCGTGACGTACGT
ATCGA
>header_seq2_>mno
ATCGGCGGTATTTA
ACGGTGGA
>header_seq3_>pqr
ATCGATCAGTACGA
ACGATGACGAT

range.txt file like this:

4 -6
7- 8
2- 5

the possible outcome should be like this:

>header_seq1_>xyz
ACA
>header_seq2_>mno
GG
>header_seq3_>pqr
TCGA

i write a code which follows as

grep -v ">" pv.fasta |sed ':a;N;$!ba;s/\n//g' | cut -c34655-36384

but it gives same region ( takes same range 34655 to 36384) for all the sequeces and output follows as :

TGAAAACCTTATATTCCCTGAGGAGGTTCTACCCCGTGGAAACGCTCTTTAATGGAACTTTAGCTTTAGCTGGTCGTGACCAAGAAACCACCGGTTTCGCTTGGTGGGCCGGGAATGCCCGACTTATCAATTTATCTGGTAAACTACTTGGGGCTCATGTAGCCCATGCCGGATTAATCGTATTCTGGGCCGGAGCAATGACCCTATTTGAAGTGGCTCATTTCCTACCAGAGAAACCCATGTATGAACAAGGCTTGATTTTACTTCCGCACCTAGCGACTCTAGGTTGGGGGGTAGGTCCTGGTGGGGAAGTTATAGATACCTTTCCATACTTTGTATCTGGAGTACTTCACCTAATTTCCTCCGCAGTATTGGGCTTTGGCGGTATTTATCATGCACTTCTGGGCCCCGAGACTCTTGAAGAATCTTTTCCATTCTTCGGTTATGTATGGAAAGATAGAAATAAAATGACCACAATTTTAGGTATTCACTTAGTCTTGTTAGGTATAGGTGCTTTTCTTCTAGTATTCAAGGCTCTTTATTTTGGAGGCGTATATGATACCTGGGCTCCGGGCGGGGGGGATGTAAGAAAAATAACCAACTTAACCCTCAGTCCAGGCGTTATATTTGGTTATTTACTAAAATCGCCCTTTGGAGGAGAAGGCTGGATTGTTAGTGTGGATGATTTGGAAGATATAATTGGAGGGCATGTATGGTTAGGCTCCATTTGTATACTTGGTGGAGTTTGGCATATCTTAACCAAACCTTTTGCATGGGCTCGCCGTGCACTTGTATGGTCTGGTGAGGCTTACTTGTCTTATAGTTTAGGGGCTTTATCTGTCTTTGGCTTCATTGCTTGTTGCTTTGTATGGTTCAACAACACCGCCTATCCTAGTGAGTTTTACGGGCCAACTGGGCCAGAAGCTTCTCAAGCTCAAGCATTTACTTTTCTAGTTAGAGACCAACGTCTTGGGGCTAATGTAGGATCTGCTCAAGGACCTACTGGTTTAGGTAAATATCTAATGCGCTCTCCGACTGGAGAAGTGATTTTTGGAGGAGAAACTATGCGCTTTTGGGATCTGCGCGCTCCTTGGTTAGAACCTCTAAGGGGTCCAAATGGTTTGGACTTGAGTAGGCTGAAAAAAGACATACAACCTTGGCAAGAACGGCGTTCCGCAGAATATATGACTCATGCTCCTTTAGGTTCTTTAAATTCCGTGGGTGGCGTAGCTACCGAGATCAATGCAGTCAACTATGTCTCTCCTAGAAGTTGGTTAGCTACTTCGCATTTTGTTCTCGGGTTCTTCCTATTCGTAGGTCATCTGTGGCACGCGGGAAGGGCTCGTGCAGCTGCAGCAGGATTTGAAAAAGGAATCGATCGCGATTTTGAACCTGTTCTTTCCATGACCCCTCTTAACTGAGACAGGCGATCAGATGTTTGACATAGGAATCTCCAACATACAATACATATTGGGACCGGGTCATACTTAAAAAGTATTCGTTATTCCTTATCTTTTTTTTTTCAATCTATATCTAAATCGAATCTATTTTTTCTGGCTCGGCTATTCCACCTAGCCGAGCCATTCCGCCTTTTGGCCGGGCAAAACCGATAAAGAAATCTATTCGTCGAGCAAAAAAAGGAGAGAGAGGGATTCGAACCCTCGATAGTTCTTTGTTTAGAACTATACCGGTTTTCAAGACCGGAGCTATCAACCGCTCGGCCATCTCTC

rna-seq sed fasta sequence extract sequence

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updated 9.6 years ago by Paul

• written 9.6 years ago by ak93sharma •

This looks like one of the problems from your classroom assignments.

What do you mean by "I am able to do this for only a single sequence by providing its range its takes huge time if I extract particular region one by one" ? Are you doing it manually ? What else did you try? Did you try to write a program, if yes, share the code and the exact error message. Or, did you try to google?

Biostars is not meant for providing ready answers.

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written 9.6 years ago by lakhujanivijay

i have already written a code which gives me same region from all sequence , my code follows as

grep -v ">" pv.fasta |sed ':a;N;$!ba;s/\n//g' | cut -c34655-36384

and gives output :

TGAAAACCTTATATTCCCTGAGGAGGTTCTACCCCGTGGAAACGCTCTTTAATGGAACTTTAGCTTTAGCTGGTCGTGACCAAGAAACCACCGGTTTCGCTTGGTGGGCCGGGAATGCCCGACTTATCAATTTATCTGGTAAACTACTTGGGGCTCATGTAGCCCATGCCGGATTAATCGTATTCTGGGCCGGAGCAATGACCCTATTTGAAGTGGCTCATTTCCTACCAGAGAAACCCATGTATGAACAAGGCTTGATTTTACTTCCGCACCTAGCGACTCTAGGTTGGGGGGTAGGTCCTGGTGGGGAAGTTATAGATACCTTTCCATACTTTGTATCTGGAGTACTTCACCTAATTTCCTCCGCAGTATTGGGCTTTGGCGGTATTTATCATGCACTTCTGGGCCCCGAGACTCTTGAAGAATCTTTTCCATTCTTCGGTTATGTATGGAAAGATAGAAATAAAATGACCACAATTTTAGGTATTCACTTAGTCTTGTTAGGTATAGGTGCTTTTCTTCTAGTATTCAAGGCTCTTTATTTTGGAGGCGTATATGATACCTGGGCTCCGGGCGGGGGGGATGTAAGAAAAATAACCAACTTAACCCTCAGTCCAGGCGTTATATTTGGTTATTTACTAAAATCGCCCTTTGGAGGAGAAGGCTGGATTGTTAGTGTGGATGATTTGGAAGATATAATTGGAGGGCATGTATGGTTAGGCTCCATTTGTATACTTGGTGGAGTTTGGCATATCTTAACCAAACCTTTTGCATGGGCTCGCCGTGCACTTGTATGGTCTGGTGAGGCTTACTTGTCTTATAGTTTAGGGGCTTTATCTGTCTTTGGCTTCATTGCTTGTTGCTTTGTATGGTTCAACAACACCGCCTATCCTAGTGAGTTTTACGGGCCAACTGGGCCAGAAGCTTCTCAAGCTCAAGCATTTACTTTTCTAGTTAGAGACCAACGTCTTGGGGCTAATGTAGGATCTGCTCAAGGACCTACTGGTTTAGGTAAATATCTAATGCGCTCTCCGACTGGAGAAGTGATTTTTGGAGGAGAAACTATGCGCTTTTGGGATCTGCGCGCTCCTTGGTTAGAACCTCTAAGGGGTCCAAATGGTTTGGACTTGAGTAGGCTGAAAAAAGACATACAACCTTGGCAAGAACGGCGTTCCGCAGAATATATGACTCATGCTCCTTTAGGTTCTTTAAATTCCGTGGGTGGCGTAGCTACCGAGATCAATGCAGTCAACTATGTCTCTCCTAGAAGTTGGTTAGCTACTTCGCATTTTGTTCTCGGGTTCTTCCTATTCGTAGGTCATCTGTGGCACGCGGGAAGGGCTCGTGCAGCTGCAGCAGGATTTGAAAAAGGAATCGATCGCGATTTTGAACCTGTTCTTTCCATGACCCCTCTTAACTGAGACAGGCGATCAGATGTTTGACATAGGAATCTCCAACATACAATACATATTGGGACCGGGTCATACTTAAAAAGTATTCGTTATTCCTTATCTTTTTTTTTTCAATCTATATCTAAATCGAATCTATTTTTTCTGGCTCGGCTATTCCACCTAGCCGAGCCATTCCGCCTTTTGGCCGGGCAAAACCGATAAAGAAATCTATTCGTCGAGCAAAAAAAGGAGAGAGAGGGATTCGAACCCTCGATAGTTCTTTGTTTAGAACTATACCGGTTTTCAAGACCGGAGCTATCAACCGCTCGGCCATCTCTC

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written 9.6 years ago by ak93sharma •

samtools faidx is your friend (as are biopython and pyfasta).

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written 9.6 years ago by Devon Ryan

For basic tasks like this, there are already a couple of tools present which are open source. For your task, checkout, bedtools getfasta here.

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written 9.6 years ago by lakhujanivijay

bedtools getfasta isn't going to help OP. He needs a different interval from each fasta entry.

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written 9.6 years ago by WouterDeCoster

This could easily be done using a (Bio)python script. Let me know if you can't figure it out.

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written 9.6 years ago by WouterDeCoster

1 answer

Hi,

what about to try some pure bash scripting. Lets assume your range is called range.txt a fasta file is fasta.fa. Put all files in one directory and make solution.sh executable (chmod +x solution.sh):

cat solution.sh

#!/bin/bash
lines=$(awk 'END {print NR}' range.txt)
for ((a=1; a<= $lines ; a++))
 do 
 number=$(awk -v lines=$a 'NR == lines' range.txt)
 grep -v ">" fasta.fa | awk -v lines=$a 'NR == lines' | cut -c$number
done;

run it like

./solution.sh

This would be probably slow for very huge fasta files.

Cheers.

• 0 views • link

updated 9.2 years ago by Ram

• written 9.6 years ago by Paul

@Paul , Thank you so much, its works well. I made a sample file before running it to a huge fasta file containing 716 genomes.

sample fasta and range file.

cat fasta.fa
>header1
ABCDEFGHIJGGGGGGGGGGG
>header2
KLMNOPQRSTUVWCCCCCCC


cat range.txt 
4-6
2-5

I made code like this

cat fasta.fa |sed -n 2~2p |sed '1q;d'|cut -c4-6
output:
DEF
cat fasta.fa |sed -n 2~2p |sed '2q;d'|cut -c2-5
output:
LMNO

I want to pass variable $L and $R in such way in my code that desired result will come, please help me out.

  R in `cat range.txt`
       L in {1..2}


cat fasta.fa |sed -n 2~2p |sed '$Lq;d'|cut -c$R

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written 9.6 years ago by ak93sharma •

You are welcome. I tried it on the huge fasta file and it seems to me it works fast. Did my solution works?

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written 9.6 years ago by Paul