Python3 – IndexError: string index out of range

import sys
from Bio import SeqIO

f = sys.argv[1]

seq_records = SeqIO.parse(f, 'fasta')
refseq_record = next(seq_records)

for seq_record in seq_records:
    for i in range(0, len(refseq_record)):
        nt1 = refseq_record[i]
        nt2 = seq_record[i]
        if nt1 != nt2:
            print (seq_record.id, i+1, nt2, nt1)

Hello,
I get IndexError: string index out of range error at line 12:
nt2 = seq_record[i]

Could you please help me with this?

>Solution :

Force the min value length between the reference sequence and the current sequence

import sys
from Bio import SeqIO

f = sys.argv[1]

seq_records = SeqIO.parse(f, 'fasta')
refseq_record = next(seq_records)

for seq_record in seq_records:
    min_length = min(len(refseq_record), len(seq_record))
    for i in range(0, min_length):
        nt1 = refseq_record[i]
        nt2 = seq_record[i]
        if nt1 != nt2:
            print(seq_record.id, i + 1, nt2, nt1)