Adding an attribute to GFF3 file

Question

I failed to add Note=Gene description to mRNA attribute with the below code:

#!/usr/bin/python3
import click
import gffutils
import gffutils.gffwriter as gffwriter

@click.command()
@click.option('--gff3', help="Provide GFF3 file", required=True)
@click.option('--keep', help="Keep GFF3 file", required=True)
@click.option('--reject', help="Reject GFF3 file", required=True)
def run(gff3, keep, reject):
    #db = gffutils.create_db(gff3, dbfn='data/test.db', force=True, keep_order=True, merge_strategy='merge',
    #                        sort_attribute_values=True)

    db = gffutils.FeatureDB('data/test.db', keep_order=True)
    for gene in db.features_of_type('gene', order_by='start'):
        print(gene)
        for i in db.children(gene, featuretype='mRNA', order_by='start'):
            print(i)
            print(i.id)
            print(i.attributes['Note']=["Gene description"])
            db.update([i])

I got the following error:

File "/projects/bioinf-scripts/mod_braker_gff3.py", line 20
    print(i.attributes['Note']=["Gene description"])
         ^
SyntaxError: keyword can't be an expression

What did I miss?

Thank you in advance

Answer 1

You are printing the attribute before setting it, that's why it's complaining. So instead of this:

    print(i.attributes['Note']=["Gene description"])

Set it first and then print:

i.attributes['Note']=["Gene description"]
print(i)