Question: Changing the record id in a FASTA file using BioPython
5
3.5 years ago by
Jeroen Van Goey2.2k
Ghent, Belgium
Jeroen Van Goey2.2k wrote:

I have the following FASTA file, original.fasta:

    >foo
GCTCACACATAGTTGATGCAGATGTTGAATTCACTATGAGGTGGGAGGATGTAGGGCCA

I need to change the record id from foo to bar, so I wrote the following code:

    from Bio import SeqIO

original_file = r"path\to\original.fasta"
corrected_file = r"path\to\corrected.fasta"

with open(original_file) as original, open(corrected_file, 'w') as corrected:
records = SeqIO.parse(original_file, 'fasta')
for record in records:
print record.id             # prints 'foo'
if record.id == 'foo':
record.id = 'bar'
print record.id             # prints 'bar' as expected
SeqIO.write(record, corrected, 'fasta')

We printed the record id before and after the change, and get the expected result. We can even doublecheck by reading in the corrected file again with BioPython and printing out the record id:

    with open(corrected_file) as corrected:
for record in SeqIO.parse(corrected, 'fasta'):
print record.id                  # prints 'bar', as expected


However, if we open the corrected file in a text editor, we see that the record id is not bar but  bar foo:

    >bar foo
GCTCACACATAGTTGATGCAGATGTTGAATTCACTATGAGGTGGGAGGATGTAGGGCCA

We can confirm that this is what is written to the file if we read the file using plain Python:

    with open(corrected_file) as corrected:
print corrected.readlines()[0][1:] # prints 'bar foo'

Is this a bug in BioPython? And if not, what did I do wrong and how do I change the record id in a FASTA file using BioPython?

biopython • 4.7k views
modified 21 months ago by lakshmi.bioinformatics20 • written 3.5 years ago by Jeroen Van Goey2.2k
5
3.5 years ago by
samuelmiver400
Centre for Genomic Regulation (Barcelona, Spain)
samuelmiver400 wrote:

You have to change the record.description to achieve your goal:

from Bio import SeqIO

original_file = "./original.fasta"
corrected_file = "./corrected.fasta"

with open(original_file) as original, open(corrected_file, 'w') as corrected:
records = SeqIO.parse(original_file, 'fasta')
for record in records:
print record.id
if record.id == 'foo':
record.id = 'bar'
record.description = 'bar' # <- Add this line
print record.id
SeqIO.write(record, corrected, 'fasta')

what happens if the original sequences has descriptions?

ADD REPLYlink modified 3.5 years ago • written 3.5 years ago by jrbustosm0

The description (in a FASTA file) is the line distinguished from the sequence data by a greater-than (">") symbol in the first column. In the problem case, 'foo' is the description and that is the word we want to change so you need to use the record.description change to convert it to 'bar'.

ADD REPLYlink modified 3.5 years ago • written 3.5 years ago by samuelmiver400
0
21 months ago by
India
lakshmi.bioinformatics20 wrote:

I want to change the names of 40k fasta files using a dictionary record containing the names to be changed how to do in bippython