change order of FASTA seqs, based on ID list

[ssully]

Is there any tool for doing this -- change the order of sequences in a FASTA file according to the order of a list of sequence IDs in another file?

Seaview will reorder sequences based on sequence order in a tree, but that is very specific case. I'd like something more general.

I know I could make a db of the FASTA set and use something like a batch NCBI blastdbcmd to extract the sequences in the order I want, but I'm hoping something less time consuming exists.

[JackieBadger]

Without being a code monkey I would have to do it a slightly long-winded way:
1. Use Galaxy web portal to change Fasta-Tabular
2.Copy and Paste this list into excel
3. Use the Match+Index function in excel to create the new list
4. save to .txt, and use Galaxy to convert to FASTA

[dariober]

Is there any tool for doing this -- change the order of sequences in a FASTA file according to the order of a list of sequence IDs in another file?

Hi- The script below should do what you want. Save it as reorder_fasta.py (or whatever you want) and execute it as

reorder_fasta.py seq.fasta ref.txt

. See the help in the script itself for more detail and example.

Hope this helps!
Dario

Code for reorder_fasta.py

#!/usr/bin/env python

import sys

docstring= """DESCRIPTION
    Reorder the sequences in a FASTA file according to the order given in a reference
    file. The reference file has one sequence name per line.
USAGE
    reorder_fasta.py <file.fasta> <file.reference>

----------- EXAMPLE -------------
## fasta file
echo '>second_seq
AAAAAAAAAAAA
AAAAAAAAAAAA
AAAA
>first_seq
TTTTTTTTTTTTTT
TTTTTTTTTTTTTT
TTTTTTTTT
>third_seq
CCCCCCCCCCCCCCCCCC' > seq.fasta

## reference file
echo 'first_seq
second_seq
third_seq' > ref.txt

## Reorder fasta according to reference:
reorder_fasta.py seq.fasta ref.txt
>first_seq
TTTTTTTTTTTTTT
TTTTTTTTTTTTTT
TTTTTTTTT
>second_seq
AAAAAAAAAAAA
AAAAAAAAAAAA
AAAA
>third_seq
CCCCCCCCCCCCCCCCCC
"""

if len(sys.argv) != 3:
    sys.exit(docstring)

fasta= open(sys.argv[1])
ref= open(sys.argv[2])

seq_dict= {}
while True:
    line= fasta.readline()
    if line == '':
        break
    if line.strip().startswith('>'):
        seq_name= line.strip()[1:]
        seq_dict[seq_name]= []
    else:
        seq_dict[seq_name].append(line.strip())
fasta.close()
for seq_name in ref:
    seq_name= seq_name.strip()
    print('>' + seq_name)
    print('\n'.join(seq_dict[seq_name]))
ref.close()
sys.exit()