pip install biopython python from Bio import SeqIO records = SeqIO.parse("sequence.fasta", "fasta") for record in records: sequence = record.seq base_counts = sequence.count("A"), sequence.count("C"), sequence.count("G"), sequence.count("T") print("Sequence: {}".format(sequence)) print("Base frequencies: A={}, C={}, G={}, T={}".format(*base_counts))