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#!/usr/bin/env python
"""Example of generating a substitution matrix from an alignment.
"""
# standard library
from __future__ import print_function
# Biopython
from Bio import SubsMat
from Bio import AlignIO
from Bio.Alphabet import IUPAC, Gapped
from Bio.Align import AlignInfo
# get an alignment object from a Clustalw alignment output
c_align = AlignIO.read('protein.aln', 'clustal',
alphabet=Gapped(IUPAC.protein))
summary_align = AlignInfo.SummaryInfo(c_align)
# get a replacement dictionary and accepted replacement matrix
# exclude all amino acids that aren't charged polar
replace_info = summary_align.replacement_dictionary(["G", "A", "V", "L", "I",
"M", "P", "F", "W", "S",
"T", "N", "Q", "Y", "C"])
my_arm = SubsMat.SeqMat(replace_info)
print(replace_info)
my_lom = SubsMat.make_log_odds_matrix(my_arm)
print('log_odds_mat: %s' % my_lom)
my_lom.print_mat()
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