def _force_alphabet(record_iterator, alphabet):
"""Iterate over records, over-riding the alphabet (PRIVATE)."""
# Assume the alphabet argument has been pre-validated
given_base_class = _get_base_alphabet(alphabet).__class__
for record in record_iterator:
if isinstance(_get_base_alphabet(record.seq.alphabet),
given_base_class):
record.seq.alphabet = alphabet
yield record
else:
raise ValueError("Specified alphabet %r clashes with "
"that determined from the file, %r"
% (alphabet, record.seq.alphabet))
def _force_alphabet(record_iterator, alphabet):
"""Iterate over records, over-riding the alphabet (PRIVATE)."""
#Assume the alphabet argument has been pre-validated
given_base_class = _get_base_alphabet(alphabet).__class__
for record in record_iterator:
if isinstance(_get_base_alphabet(record.seq.alphabet),
given_base_class):
record.seq.alphabet = alphabet
yield record
else:
raise ValueError("Specified alphabet %s clashes with "\
"that determined from the file, %s" \
% (repr(alphabet), repr(record.seq.alphabet)))
def _force_alphabet(alignment_iterator, alphabet):
"""Iterate over alignments, over-riding the alphabet (PRIVATE)."""
# Assume the alphabet argument has been pre-validated
given_base_class = _get_base_alphabet(alphabet).__class__
for align in alignment_iterator:
if not isinstance(_get_base_alphabet(align._alphabet),
given_base_class):
raise ValueError("Specified alphabet %s clashes with "
"that determined from the file, %s" %
(repr(alphabet), repr(align._alphabet)))
for record in align:
if not isinstance(_get_base_alphabet(record.seq.alphabet),
given_base_class):
raise ValueError("Specified alphabet %s clashes with "
"that determined from the file, %s" %
(repr(alphabet), repr(record.seq.alphabet)))
record.seq.alphabet = alphabet
align._alphabet = alphabet
yield align
print("Name: %s" % cur_record.name)
print("Description %s" % cur_record.description)
print("Annotations***")
ann_keys = sorted(cur_record.annotations)
for ann_key in ann_keys:
if ann_key != 'references':
print("Key: %s" % ann_key)
print("Value: %s" % cur_record.annotations[ann_key])
else:
print("References*")
for reference in cur_record.annotations[ann_key]:
print(str(reference))
print("Features")
for feature in cur_record.features:
print(feature)
if isinstance(_get_base_alphabet(cur_record.seq.alphabet),
ProteinAlphabet):
assert feature.strand is None
else:
# Assuming no mixed strand examples...
assert feature.strand is not None
print("DB cross refs %s" % cur_record.dbxrefs)
elif isinstance(parser, GenBank.RecordParser):
print("***Record from %s with the RecordParser" %
filename.split(os.path.sep)[-1])
print("sequence length: %i" % len(cur_record.sequence))
print("locus: %s" % cur_record.locus)
print("definition: %s" % cur_record.definition)
print("accession: %s" % cur_record.accession)
for reference in cur_record.references:
print("reference title: %s" % reference.title)
print("Name: %s" % cur_record.name)
print("Description %s" % cur_record.description)
print("Annotations***")
ann_keys = sorted(cur_record.annotations)
for ann_key in ann_keys:
if ann_key != "references":
print("Key: %s" % ann_key)
print("Value: %s" % cur_record.annotations[ann_key])
else:
print("References*")
for reference in cur_record.annotations[ann_key]:
print(str(reference))
print("Feaures")
for feature in cur_record.features:
print(feature)
if isinstance(_get_base_alphabet(cur_record.seq.alphabet), ProteinAlphabet):
assert feature.strand is None
else:
# Assuming no mixed strand examples...
assert feature.strand is not None
print("DB cross refs %s" % cur_record.dbxrefs)
elif isinstance(parser, GenBank.RecordParser):
print("***Record from %s with the RecordParser" % filename.split(os.path.sep)[-1])
print("sequence length: %i" % len(cur_record.sequence))
print("locus: %s" % cur_record.locus)
print("definition: %s" % cur_record.definition)
print("accession: %s" % cur_record.accession)
for reference in cur_record.references:
print("reference title: %s" % reference.title)
for feature in cur_record.features:
def build(pro_align, nucl_seqs, corr_dict=None, gap_char='-', unknown='X',
codon_table=default_codon_table, alphabet=None,
complete_protein=False, anchor_len=10, max_score=10):
"""Build a codon alignment from protein alignment and corresponding nucleotides.
Arguments:
- pro_align - a protein MultipleSeqAlignment object
- nucl_align - an object returned by SeqIO.parse or SeqIO.index
or a collection of SeqRecord.
- alphabet - alphabet for the returned codon alignment
- corr_dict - a dict that maps protein id to nucleotide id
- complete_protein - whether the sequence begins with a start
codon
- frameshift - whether to apply frameshift detection
Return a CodonAlignment object
>>> from Bio.Alphabet import IUPAC
>>> from Bio.Seq import Seq
>>> from Bio.SeqRecord import SeqRecord
>>> from Bio.Align import MultipleSeqAlignment
>>> seq1 = SeqRecord(Seq('TCAGGGACTGCGAGAACCAAGCTACTGCTGCTGCTGGCTGCGCTCTGCGCCGCAGGTGGGGCGCTGGAG',
... alphabet=IUPAC.IUPACUnambiguousDNA()), id='pro1')
>>> seq2 = SeqRecord(Seq('TCAGGGACTTCGAGAACCAAGCGCTCCTGCTGCTGGCTGCGCTCGGCGCCGCAGGTGGAGCACTGGAG',
... alphabet=IUPAC.IUPACUnambiguousDNA()), id='pro2')
>>> pro1 = SeqRecord(Seq('SGTARTKLLLLLAALCAAGGALE', alphabet=IUPAC.protein),id='pro1')
>>> pro2 = SeqRecord(Seq('SGTSRTKRLLLLAALGAAGGALE', alphabet=IUPAC.protein),id='pro2')
>>> aln = MultipleSeqAlignment([pro1, pro2])
>>> codon_aln = build(aln, [seq1, seq2])
>>> print(codon_aln)
CodonAlphabet(Standard) CodonAlignment with 2 rows and 69 columns (23 codons)
TCAGGGACTGCGAGAACCAAGCTACTGCTGCTGCTGGCTGCGCTCTGCGCCGCAGGT...GAG pro1
TCAGGGACTTCGAGAACCAAGCG-CTCCTGCTGCTGGCTGCGCTCGGCGCCGCAGGT...GAG pro2
"""
# TODO
# add an option to allow the user to specify the returned object?
from Bio.Alphabet import ProteinAlphabet
from Bio.Align import MultipleSeqAlignment
# check the type of object of pro_align
if not isinstance(pro_align, MultipleSeqAlignment):
raise TypeError("the first argument should be a MultipleSeqAlignment "
"object")
# check the alphabet of pro_align
for pro in pro_align:
if not isinstance(_get_base_alphabet(pro.seq.alphabet), ProteinAlphabet):
raise TypeError("Alphabet Error!\nThe input alignment should be "
"a *PROTEIN* alignemnt, found %r" % pro.seq.alphabet)
if alphabet is None:
alphabet = _get_codon_alphabet(codon_table, gap_char=gap_char)
# check whether the number of seqs in pro_align and nucl_seqs is
# the same
pro_num = len(pro_align)
if corr_dict is None:
if nucl_seqs.__class__.__name__ == "generator":
# nucl_seqs will be a tuple if read by SeqIO.parse()
nucl_seqs = tuple(nucl_seqs)
nucl_num = len(nucl_seqs)
if pro_num > nucl_num:
raise ValueError("Higher Number of SeqRecords in Protein Alignment "
"({0}) than the Number of Nucleotide SeqRecords "
"({1}) are found!".format(pro_num, nucl_num))
# Determine the protein sequences and nucl sequences
# correspondence. If nucl_seqs is a list, tuple or read by
# SeqIO.parse(), we assume the order of sequences in pro_align
# and nucl_seqs are the same. If nucl_seqs is a dict or read by
# SeqIO.index(), we match seqs in pro_align and those in
# nucl_seq by their id.
if nucl_seqs.__class__.__name__ in ("_IndexedSeqFileDict", "dict"):
corr_method = 1
elif nucl_seqs.__class__.__name__ in ("list", "tuple"):
corr_method = 0
else:
raise TypeError("Nucl Sequences Error, Unknown type to assign "
"correspondence method")
else:
if not isinstance(corr_dict, dict):
raise TypeError("corr_dict should be a dict that corresponds "
"protein id to nucleotide id!")
if len(corr_dict) >= pro_num:
# read by SeqIO.parse()
if nucl_seqs.__class__.__name__ == "generator":
from Bio import SeqIO
nucl_seqs = SeqIO.to_dict(nucl_seqs)
elif nucl_seqs.__class__.__name__ in ("list", "tuple"):
nucl_seqs = dict((i.id, i) for i in nucl_seqs)
# nucl_seqs = {i.id: i for i in nucl_seqs}
elif nucl_seqs.__class__.__name__ in \
("_IndexedSeqFileDict", "dict"):
pass
else:
raise TypeError("Nucl Sequences Error, Unknown type of "
"Nucleotide Records!")
corr_method = 2
else:
raise RuntimeError("Number of items in corr_dict ({0}) is less "
"than number of protein records "
"({1})".format(len(corr_dict), pro_num))
# set up pro-nucl correspondence based on corr_method
# corr_method = 0, consecutive pairing
if corr_method == 0:
pro_nucl_pair = zip(pro_align, nucl_seqs)
# corr_method = 1, keyword pairing
elif corr_method == 1:
nucl_id = set(nucl_seqs.keys())
pro_id = set(i.id for i in pro_align)
# check if there is pro_id that does not have a nucleotide match
if pro_id - nucl_id:
diff = pro_id - nucl_id
raise ValueError("Protein Record {0} cannot find a nucleotide "
"sequence match, please check the "
"id".format(', '.join(diff)))
else:
pro_nucl_pair = []
for pro_rec in pro_align:
pro_nucl_pair.append((pro_rec, nucl_seqs[pro_rec.id]))
# corr_method = 2, dict pairing
elif corr_method == 2:
pro_nucl_pair = []
for pro_rec in pro_align:
try:
nucl_id = corr_dict[pro_rec.id]
except KeyError:
print("Protein record (%s) is not in corr_dict!" % pro_rec.id)
exit(1)
pro_nucl_pair.append((pro_rec, nucl_seqs[nucl_id]))
codon_aln = []
shift = False
for pair in pro_nucl_pair:
# Beware that the following span corresponds to an ungapped
# nucleotide sequence.
corr_span = _check_corr(pair[0], pair[1], gap_char=gap_char,
codon_table=codon_table,
complete_protein=complete_protein,
anchor_len=anchor_len)
if not corr_span:
raise ValueError("Protein Record {0} and Nucleotide Record {1} do"
" not match!".format(pair[0].id, pair[1].id))
else:
codon_rec = _get_codon_rec(pair[0], pair[1], corr_span,
alphabet=alphabet,
complete_protein=False,
codon_table=codon_table,
max_score=max_score)
codon_aln.append(codon_rec)
if corr_span[1] == 2:
shift = True
if shift:
return CodonAlignment(_align_shift_recs(codon_aln), alphabet=alphabet)
else:
return CodonAlignment(codon_aln, alphabet=alphabet)
def _check_corr(pro, nucl, gap_char='-', codon_table=default_codon_table,
complete_protein=False, anchor_len=10):
"""Check if the nucleotide can be translated into the protein (PRIVATE).
Expects two SeqRecord objects.
"""
import re
from Bio.Alphabet import NucleotideAlphabet
if not isinstance(pro, SeqRecord) or not isinstance(nucl, SeqRecord):
raise TypeError("_check_corr accepts two SeqRecord object. Please "
"check your input.")
def get_alpha(alpha):
if hasattr(alpha, 'alphabet'):
return get_alpha(alpha.alphabet)
else:
return alpha
if not isinstance(_get_base_alphabet(get_alpha(nucl.seq.alphabet)),
NucleotideAlphabet):
raise TypeError("Alphabet for nucl should be an instance of "
"NucleotideAlphabet, {0} "
"detected".format(str(nucl.seq.alphabet)))
aa2re = _get_aa_regex(codon_table)
pro_re = ""
for aa in pro.seq:
if aa != gap_char:
pro_re += aa2re[aa]
nucl_seq = str(nucl.seq.upper().ungap(gap_char))
match = re.search(pro_re, nucl_seq)
if match:
# mode = 0, direct match
return (match.span(), 0)
else:
# Might caused by mismatches or frameshift, using anchors to
# have a try
# anchor_len = 10 # adjust this value to test performance
pro_seq = str(pro.seq).replace(gap_char, "")
anchors = [pro_seq[i:(i + anchor_len)] for i in
range(0, len(pro_seq), anchor_len)]
# if the last anchor is less than the specified anchor
# size, we combine the penultimate and the last anchor
# together as the last one.
# TODO: modify this to deal with short sequence with only
# one anchor.
if len(anchors[-1]) < anchor_len:
anchors[-1] = anchors[-2] + anchors[-1]
pro_re = []
anchor_distance = 0
anchor_pos = []
for i, anchor in enumerate(anchors):
this_anchor_len = len(anchor)
qcodon = ""
fncodon = ""
# dirty code to deal with the last anchor
# as the last anchor is combined in the steps
# above, we need to get the true last anchor to
# pro_re
if this_anchor_len == anchor_len:
for aa in anchor:
if complete_protein and i == 0:
qcodon += _codons2re(codon_table.start_codons)
fncodon += aa2re['X']
continue
qcodon += aa2re[aa]
fncodon += aa2re['X']
match = re.search(qcodon, nucl_seq)
elif this_anchor_len > anchor_len:
last_qcodon = ""
last_fcodon = ""
for j in range(anchor_len, len(anchor)):
last_qcodon += aa2re[anchor[j]]
last_fcodon += aa2re['X']
match = re.search(last_qcodon, nucl_seq)
# build full_pro_re from anchors
if match:
anchor_pos.append((match.start(), match.end(), i))
if this_anchor_len == anchor_len:
pro_re.append(qcodon)
else:
pro_re.append(last_qcodon)
else:
if this_anchor_len == anchor_len:
pro_re.append(fncodon)
else:
pro_re.append(last_fcodon)
full_pro_re = "".join(pro_re)
match = re.search(full_pro_re, nucl_seq)
if match:
# mode = 1, mismatch
return (match.span(), 1)
else:
# check frames of anchors
# ten frameshift events are allowed in a sequence
first_anchor = True
shift_id_pos = 0
# check the first anchor
if first_anchor and anchor_pos[0][2] != 0:
shift_val_lst = [1, 2, 3 * anchor_len - 2, 3 * anchor_len - 1, 0]
sh_anc = anchors[0]
for shift_val in shift_val_lst:
if shift_val == 0:
qcodon = None
break
if shift_val in (1, 2):
sh_nuc_len = anchor_len * 3 + shift_val
elif shift_val in (3 * anchor_len - 2, 3 * anchor_len - 1):
sh_nuc_len = anchor_len * 3 - (3 * anchor_len - shift_val)
if anchor_pos[0][0] >= sh_nuc_len:
sh_nuc = nucl_seq[anchor_pos[0][0] - sh_nuc_len:anchor_pos[0][0]]
else:
# this is unlikely to produce the correct output
sh_nuc = nucl_seq[:anchor_pos[0][0]]
qcodon, shift_id_pos = _get_shift_anchor_re(sh_anc, sh_nuc,
shift_val,
aa2re,
anchor_len,
shift_id_pos)
if qcodon is not None and qcodon != -1:
# pro_re[0] should be '.'*anchor_len, therefore I
# replace it.
pro_re[0] = qcodon
break
if qcodon == -1:
warnings.warn("first frameshift detection failed for "
"{0}".format(nucl.id), BiopythonWarning)
# check anchors in the middle
for i in range(len(anchor_pos) - 1):
shift_val = (anchor_pos[i + 1][0] - anchor_pos[i][0]) % \
(3 * anchor_len)
sh_anc = "".join(anchors[anchor_pos[i][2]:anchor_pos[i + 1][2]])
sh_nuc = nucl_seq[anchor_pos[i][0]:anchor_pos[i + 1][0]]
qcodon = None
if shift_val != 0:
qcodon, shift_id_pos = _get_shift_anchor_re(sh_anc, sh_nuc,
shift_val,
aa2re,
anchor_len,
shift_id_pos)
if qcodon is not None and qcodon != -1:
pro_re[anchor_pos[i][2]:anchor_pos[i + 1][2]] = [qcodon]
qcodon = None
elif qcodon == -1:
warnings.warn("middle frameshift detection failed for "
"{0}".format(nucl.id), BiopythonWarning)
# check the last anchor
if anchor_pos[-1][2] + 1 == len(anchors) - 1:
sh_anc = anchors[-1]
this_anchor_len = len(sh_anc)
shift_val_lst = [1, 2, 3 * this_anchor_len - 2, 3 * this_anchor_len - 1, 0]
for shift_val in shift_val_lst:
if shift_val == 0:
qcodon = None
break
if shift_val in (1, 2):
sh_nuc_len = this_anchor_len * 3 + shift_val
elif shift_val in \
(3 * this_anchor_len - 2, 3 * this_anchor_len - 1):
sh_nuc_len = this_anchor_len * 3 - (3 * this_anchor_len - shift_val)
if len(nucl_seq) - anchor_pos[-1][0] >= sh_nuc_len:
sh_nuc = nucl_seq[anchor_pos[-1][0]:anchor_pos[-1][0] + sh_nuc_len]
else:
# this is unlikely to produce the correct output
sh_nuc = nucl_seq[anchor_pos[-1][0]:]
qcodon, shift_id_pos = _get_shift_anchor_re(sh_anc, sh_nuc,
shift_val,
aa2re,
this_anchor_len,
shift_id_pos)
if qcodon is not None and qcodon != -1:
pro_re.pop()
pro_re[-1] = qcodon
break
if qcodon == -1:
warnings.warn("last frameshift detection failed for "
"{0}".format(nucl.id), BiopythonWarning)
# try global match
full_pro_re = "".join(pro_re)
match = re.search(full_pro_re, nucl_seq)
if match:
return (match.span(), 2, match)
else:
raise RuntimeError("Protein SeqRecord ({0}) and Nucleotide "
"SeqRecord ({1}) do not "
"match!".format(pro.id, nucl.id))
def build(pro_align,
nucl_seqs,
corr_dict=None,
gap_char='-',
unknown='X',
codon_table=default_codon_table,
alphabet=None,
complete_protein=False,
anchor_len=10,
max_score=10):
"""Build a codon alignment from protein alignment and corresponding nucleotides.
Arguments:
- pro_align - a protein MultipleSeqAlignment object
- nucl_align - an object returned by SeqIO.parse or SeqIO.index
or a collection of SeqRecord.
- alphabet - alphabet for the returned codon alignment
- corr_dict - a dict that maps protein id to nucleotide id
- complete_protein - whether the sequence begins with a start
codon
- frameshift - whether to apply frameshift detection
Return a CodonAlignment object
>>> from Bio.Alphabet import IUPAC
>>> from Bio.Seq import Seq
>>> from Bio.SeqRecord import SeqRecord
>>> from Bio.Align import MultipleSeqAlignment
>>> seq1 = SeqRecord(Seq('TCAGGGACTGCGAGAACCAAGCTACTGCTGCTGCTGGCTGCGCTCTGCGCCGCAGGTGGGGCGCTGGAG',
... alphabet=IUPAC.IUPACUnambiguousDNA()), id='pro1')
>>> seq2 = SeqRecord(Seq('TCAGGGACTTCGAGAACCAAGCGCTCCTGCTGCTGGCTGCGCTCGGCGCCGCAGGTGGAGCACTGGAG',
... alphabet=IUPAC.IUPACUnambiguousDNA()), id='pro2')
>>> pro1 = SeqRecord(Seq('SGTARTKLLLLLAALCAAGGALE', alphabet=IUPAC.protein),id='pro1')
>>> pro2 = SeqRecord(Seq('SGTSRTKRLLLLAALGAAGGALE', alphabet=IUPAC.protein),id='pro2')
>>> aln = MultipleSeqAlignment([pro1, pro2])
>>> codon_aln = build(aln, [seq1, seq2])
>>> print(codon_aln)
CodonAlphabet(Standard) CodonAlignment with 2 rows and 69 columns (23 codons)
TCAGGGACTGCGAGAACCAAGCTACTGCTGCTGCTGGCTGCGCTCTGCGCCGCAGGT...GAG pro1
TCAGGGACTTCGAGAACCAAGCG-CTCCTGCTGCTGGCTGCGCTCGGCGCCGCAGGT...GAG pro2
"""
# TODO
# add an option to allow the user to specify the returned object?
from Bio.Alphabet import ProteinAlphabet
from Bio.Align import MultipleSeqAlignment
# check the type of object of pro_align
if not isinstance(pro_align, MultipleSeqAlignment):
raise TypeError("the first argument should be a MultipleSeqAlignment "
"object")
# check the alphabet of pro_align
for pro in pro_align:
if not isinstance(_get_base_alphabet(pro.seq.alphabet),
ProteinAlphabet):
raise TypeError("Alphabet Error!\nThe input alignment should be "
"a *PROTEIN* alignemnt, found %r" %
pro.seq.alphabet)
if alphabet is None:
alphabet = _get_codon_alphabet(codon_table, gap_char=gap_char)
# check whether the number of seqs in pro_align and nucl_seqs is
# the same
pro_num = len(pro_align)
if corr_dict is None:
if nucl_seqs.__class__.__name__ == "generator":
# nucl_seqs will be a tuple if read by SeqIO.parse()
nucl_seqs = tuple(nucl_seqs)
nucl_num = len(nucl_seqs)
if pro_num > nucl_num:
raise ValueError(
"Higher Number of SeqRecords in Protein Alignment "
"({0}) than the Number of Nucleotide SeqRecords "
"({1}) are found!".format(pro_num, nucl_num))
# Determine the protein sequences and nucl sequences
# correspondence. If nucl_seqs is a list, tuple or read by
# SeqIO.parse(), we assume the order of sequences in pro_align
# and nucl_seqs are the same. If nucl_seqs is a dict or read by
# SeqIO.index(), we match seqs in pro_align and those in
# nucl_seq by their id.
if nucl_seqs.__class__.__name__ in ("_IndexedSeqFileDict", "dict"):
corr_method = 1
elif nucl_seqs.__class__.__name__ in ("list", "tuple"):
corr_method = 0
else:
raise TypeError("Nucl Sequences Error, Unknown type to assign "
"correspondence method")
else:
if not isinstance(corr_dict, dict):
raise TypeError("corr_dict should be a dict that corresponds "
"protein id to nucleotide id!")
if len(corr_dict) >= pro_num:
# read by SeqIO.parse()
if nucl_seqs.__class__.__name__ == "generator":
from Bio import SeqIO
nucl_seqs = SeqIO.to_dict(nucl_seqs)
elif nucl_seqs.__class__.__name__ in ("list", "tuple"):
nucl_seqs = dict((i.id, i) for i in nucl_seqs)
# nucl_seqs = {i.id: i for i in nucl_seqs}
elif nucl_seqs.__class__.__name__ in \
("_IndexedSeqFileDict", "dict"):
pass
else:
raise TypeError("Nucl Sequences Error, Unknown type of "
"Nucleotide Records!")
corr_method = 2
else:
raise RuntimeError("Number of items in corr_dict ({0}) is less "
"than number of protein records "
"({1})".format(len(corr_dict), pro_num))
# set up pro-nucl correspondence based on corr_method
# corr_method = 0, consecutive pairing
if corr_method == 0:
pro_nucl_pair = zip(pro_align, nucl_seqs)
# corr_method = 1, keyword pairing
elif corr_method == 1:
nucl_id = set(nucl_seqs.keys())
pro_id = set(i.id for i in pro_align)
# check if there is pro_id that does not have a nucleotide match
if pro_id - nucl_id:
diff = pro_id - nucl_id
raise ValueError("Protein Record {0} cannot find a nucleotide "
"sequence match, please check the "
"id".format(', '.join(diff)))
else:
pro_nucl_pair = []
for pro_rec in pro_align:
pro_nucl_pair.append((pro_rec, nucl_seqs[pro_rec.id]))
# corr_method = 2, dict pairing
elif corr_method == 2:
pro_nucl_pair = []
for pro_rec in pro_align:
try:
nucl_id = corr_dict[pro_rec.id]
except KeyError:
print("Protein record (%s) is not in corr_dict!" % pro_rec.id)
exit(1)
pro_nucl_pair.append((pro_rec, nucl_seqs[nucl_id]))
codon_aln = []
shift = False
for pair in pro_nucl_pair:
# Beware that the following span corresponds to an ungapped
# nucleotide sequence.
corr_span = _check_corr(pair[0],
pair[1],
gap_char=gap_char,
codon_table=codon_table,
complete_protein=complete_protein,
anchor_len=anchor_len)
if not corr_span:
raise ValueError("Protein Record {0} and Nucleotide Record {1} do"
" not match!".format(pair[0].id, pair[1].id))
else:
codon_rec = _get_codon_rec(pair[0],
pair[1],
corr_span,
alphabet=alphabet,
complete_protein=False,
codon_table=codon_table,
max_score=max_score)
codon_aln.append(codon_rec)
if corr_span[1] == 2:
shift = True
if shift:
return CodonAlignment(_align_shift_recs(codon_aln), alphabet=alphabet)
else:
return CodonAlignment(codon_aln, alphabet=alphabet)
def _check_corr(pro,
nucl,
gap_char='-',
codon_table=default_codon_table,
complete_protein=False,
anchor_len=10):
"""Check if the nucleotide can be translated into the protein (PRIVATE).
Expects two SeqRecord objects.
"""
import re
from Bio.Alphabet import NucleotideAlphabet
if not isinstance(pro, SeqRecord) or not isinstance(nucl, SeqRecord):
raise TypeError("_check_corr accepts two SeqRecord object. Please "
"check your input.")
def get_alpha(alpha):
if hasattr(alpha, 'alphabet'):
return get_alpha(alpha.alphabet)
else:
return alpha
if not isinstance(_get_base_alphabet(get_alpha(nucl.seq.alphabet)),
NucleotideAlphabet):
raise TypeError("Alphabet for nucl should be an instance of "
"NucleotideAlphabet, {0} "
"detected".format(str(nucl.seq.alphabet)))
aa2re = _get_aa_regex(codon_table)
pro_re = ""
for aa in pro.seq:
if aa != gap_char:
pro_re += aa2re[aa]
nucl_seq = str(nucl.seq.upper().ungap(gap_char))
match = re.search(pro_re, nucl_seq)
if match:
# mode = 0, direct match
return (match.span(), 0)
else:
# Might caused by mismatches or frameshift, using anchors to
# have a try
# anchor_len = 10 # adjust this value to test performance
pro_seq = str(pro.seq).replace(gap_char, "")
anchors = [
pro_seq[i:(i + anchor_len)]
for i in range(0, len(pro_seq), anchor_len)
]
# if the last anchor is less than the specified anchor
# size, we combine the penultimate and the last anchor
# together as the last one.
# TODO: modify this to deal with short sequence with only
# one anchor.
if len(anchors[-1]) < anchor_len:
anchors[-1] = anchors[-2] + anchors[-1]
pro_re = []
anchor_distance = 0
anchor_pos = []
for i, anchor in enumerate(anchors):
this_anchor_len = len(anchor)
qcodon = ""
fncodon = ""
# dirty code to deal with the last anchor
# as the last anchor is combined in the steps
# above, we need to get the true last anchor to
# pro_re
if this_anchor_len == anchor_len:
for aa in anchor:
if complete_protein and i == 0:
qcodon += _codons2re(codon_table.start_codons)
fncodon += aa2re['X']
continue
qcodon += aa2re[aa]
fncodon += aa2re['X']
match = re.search(qcodon, nucl_seq)
elif this_anchor_len > anchor_len:
last_qcodon = ""
last_fcodon = ""
for j in range(anchor_len, len(anchor)):
last_qcodon += aa2re[anchor[j]]
last_fcodon += aa2re['X']
match = re.search(last_qcodon, nucl_seq)
# build full_pro_re from anchors
if match:
anchor_pos.append((match.start(), match.end(), i))
if this_anchor_len == anchor_len:
pro_re.append(qcodon)
else:
pro_re.append(last_qcodon)
else:
if this_anchor_len == anchor_len:
pro_re.append(fncodon)
else:
pro_re.append(last_fcodon)
full_pro_re = "".join(pro_re)
match = re.search(full_pro_re, nucl_seq)
if match:
# mode = 1, mismatch
return (match.span(), 1)
else:
# check frames of anchors
# ten frameshift events are allowed in a sequence
first_anchor = True
shift_id_pos = 0
# check the first anchor
if first_anchor and anchor_pos[0][2] != 0:
shift_val_lst = [
1, 2, 3 * anchor_len - 2, 3 * anchor_len - 1, 0
]
sh_anc = anchors[0]
for shift_val in shift_val_lst:
if shift_val == 0:
qcodon = None
break
if shift_val in (1, 2):
sh_nuc_len = anchor_len * 3 + shift_val
elif shift_val in (3 * anchor_len - 2, 3 * anchor_len - 1):
sh_nuc_len = anchor_len * 3 - (3 * anchor_len -
shift_val)
if anchor_pos[0][0] >= sh_nuc_len:
sh_nuc = nucl_seq[anchor_pos[0][0] -
sh_nuc_len:anchor_pos[0][0]]
else:
# this is unlikely to produce the correct output
sh_nuc = nucl_seq[:anchor_pos[0][0]]
qcodon, shift_id_pos = _get_shift_anchor_re(
sh_anc, sh_nuc, shift_val, aa2re, anchor_len,
shift_id_pos)
if qcodon is not None and qcodon != -1:
# pro_re[0] should be '.'*anchor_len, therefore I
# replace it.
pro_re[0] = qcodon
break
if qcodon == -1:
warnings.warn(
"first frameshift detection failed for "
"{0}".format(nucl.id), BiopythonWarning)
# check anchors in the middle
for i in range(len(anchor_pos) - 1):
shift_val = (anchor_pos[i + 1][0] - anchor_pos[i][0]) % \
(3 * anchor_len)
sh_anc = "".join(anchors[anchor_pos[i][2]:anchor_pos[i +
1][2]])
sh_nuc = nucl_seq[anchor_pos[i][0]:anchor_pos[i + 1][0]]
qcodon = None
if shift_val != 0:
qcodon, shift_id_pos = _get_shift_anchor_re(
sh_anc, sh_nuc, shift_val, aa2re, anchor_len,
shift_id_pos)
if qcodon is not None and qcodon != -1:
pro_re[anchor_pos[i][2]:anchor_pos[i + 1][2]] = [qcodon]
qcodon = None
elif qcodon == -1:
warnings.warn(
"middle frameshift detection failed for "
"{0}".format(nucl.id), BiopythonWarning)
# check the last anchor
if anchor_pos[-1][2] + 1 == len(anchors) - 1:
sh_anc = anchors[-1]
this_anchor_len = len(sh_anc)
shift_val_lst = [
1, 2, 3 * this_anchor_len - 2, 3 * this_anchor_len - 1, 0
]
for shift_val in shift_val_lst:
if shift_val == 0:
qcodon = None
break
if shift_val in (1, 2):
sh_nuc_len = this_anchor_len * 3 + shift_val
elif shift_val in \
(3 * this_anchor_len - 2, 3 * this_anchor_len - 1):
sh_nuc_len = this_anchor_len * 3 - (
3 * this_anchor_len - shift_val)
if len(nucl_seq) - anchor_pos[-1][0] >= sh_nuc_len:
sh_nuc = nucl_seq[anchor_pos[-1][0]:anchor_pos[-1][0] +
sh_nuc_len]
else:
# this is unlikely to produce the correct output
sh_nuc = nucl_seq[anchor_pos[-1][0]:]
qcodon, shift_id_pos = _get_shift_anchor_re(
sh_anc, sh_nuc, shift_val, aa2re, this_anchor_len,
shift_id_pos)
if qcodon is not None and qcodon != -1:
pro_re.pop()
pro_re[-1] = qcodon
break
if qcodon == -1:
warnings.warn(
"last frameshift detection failed for "
"{0}".format(nucl.id), BiopythonWarning)
# try global match
full_pro_re = "".join(pro_re)
match = re.search(full_pro_re, nucl_seq)
if match:
return (match.span(), 2, match)
else:
raise RuntimeError("Protein SeqRecord ({0}) and Nucleotide "
"SeqRecord ({1}) do not "
"match!".format(pro.id, nucl.id))
def build(
pro_align,
nucl_seqs,
corr_dict=None,
gap_char="-",
unknown="X",
codon_table=default_codon_table,
alphabet=None,
complete_protein=False,
anchor_len=10,
max_score=10,
):
"""Build a codon alignment from protein alignment and corresponding nucleotides.
Arguments:
- pro_align - a protein MultipleSeqAlignment object
- nucl_seqs - an object returned by SeqIO.parse or SeqIO.index
or a collection of SeqRecord.
- alphabet - alphabet for the returned codon alignment
- corr_dict - a dict that maps protein id to nucleotide id
- complete_protein - whether the sequence begins with a start
codon
Return a CodonAlignment object.
The example below answers this Biostars question: https://www.biostars.org/p/89741/
>>> from Bio.Alphabet import generic_dna, generic_protein
>>> from Bio.Seq import Seq
>>> from Bio.SeqRecord import SeqRecord
>>> from Bio.Align import MultipleSeqAlignment
>>> from Bio.codonalign import build
>>> seq1 = SeqRecord(Seq('ATGTCTCGT', alphabet=generic_dna), id='pro1')
>>> seq2 = SeqRecord(Seq('ATGCGT', alphabet=generic_dna), id='pro2')
>>> pro1 = SeqRecord(Seq('MSR', alphabet=generic_protein), id='pro1')
>>> pro2 = SeqRecord(Seq('M-R', alphabet=generic_protein), id='pro2')
>>> aln = MultipleSeqAlignment([pro1, pro2])
>>> codon_aln = build(aln, [seq1, seq2])
>>> print(codon_aln)
CodonAlphabet(Standard) CodonAlignment with 2 rows and 9 columns (3 codons)
ATGTCTCGT pro1
ATG---CGT pro2
"""
# TODO
# add an option to allow the user to specify the returned object?
from Bio.Alphabet import ProteinAlphabet
from Bio.Align import MultipleSeqAlignment
# check the type of object of pro_align
if not isinstance(pro_align, MultipleSeqAlignment):
raise TypeError(
"the first argument should be a MultipleSeqAlignment object")
# check the alphabet of pro_align
for pro in pro_align:
if not isinstance(_get_base_alphabet(pro.seq.alphabet),
ProteinAlphabet):
raise TypeError("Alphabet Error!\nThe input alignment should be "
"a *PROTEIN* alignemnt, found %r" %
pro.seq.alphabet)
if alphabet is None:
alphabet = _get_codon_alphabet(codon_table, gap_char=gap_char)
# check whether the number of seqs in pro_align and nucl_seqs is
# the same
pro_num = len(pro_align)
if corr_dict is None:
if nucl_seqs.__class__.__name__ == "generator":
# nucl_seqs will be a tuple if read by SeqIO.parse()
nucl_seqs = tuple(nucl_seqs)
nucl_num = len(nucl_seqs)
if pro_num > nucl_num:
raise ValueError(
f"Higher Number of SeqRecords in Protein Alignment ({pro_num}) "
f"than the Number of Nucleotide SeqRecords ({nucl_num}) are found!"
)
# Determine the protein sequences and nucl sequences
# correspondence. If nucl_seqs is a list, tuple or read by
# SeqIO.parse(), we assume the order of sequences in pro_align
# and nucl_seqs are the same. If nucl_seqs is a dict or read by
# SeqIO.index(), we match seqs in pro_align and those in
# nucl_seq by their id.
if nucl_seqs.__class__.__name__ in ("_IndexedSeqFileDict", "dict"):
corr_method = 1
elif nucl_seqs.__class__.__name__ in ("list", "tuple"):
corr_method = 0
else:
raise TypeError(
"Nucl Sequences Error, Unknown type to assign correspondence method"
)
else:
if not isinstance(corr_dict, dict):
raise TypeError("corr_dict should be a dict that corresponds "
"protein id to nucleotide id!")
if len(corr_dict) >= pro_num:
# read by SeqIO.parse()
if nucl_seqs.__class__.__name__ == "generator":
from Bio import SeqIO
nucl_seqs = SeqIO.to_dict(nucl_seqs)
elif nucl_seqs.__class__.__name__ in ("list", "tuple"):
nucl_seqs = {i.id: i for i in nucl_seqs}
elif nucl_seqs.__class__.__name__ in ("_IndexedSeqFileDict",
"dict"):
pass
else:
raise TypeError(
"Nucl Sequences Error, Unknown type of Nucleotide Records!"
)
corr_method = 2
else:
raise RuntimeError(
f"Number of items in corr_dict ({len(corr_dict)}) "
f"is less than number of protein records ({pro_num})")
# set up pro-nucl correspondence based on corr_method
# corr_method = 0, consecutive pairing
if corr_method == 0:
pro_nucl_pair = zip(pro_align, nucl_seqs)
# corr_method = 1, keyword pairing
elif corr_method == 1:
nucl_id = set(nucl_seqs.keys())
pro_id = {i.id for i in pro_align}
# check if there is pro_id that does not have a nucleotide match
if pro_id - nucl_id:
diff = pro_id - nucl_id
raise ValueError(f"Protein Record {', '.join(diff)} cannot find a "
"nucleotide sequence match, please check the id")
else:
pro_nucl_pair = []
for pro_rec in pro_align:
pro_nucl_pair.append((pro_rec, nucl_seqs[pro_rec.id]))
# corr_method = 2, dict pairing
elif corr_method == 2:
pro_nucl_pair = []
for pro_rec in pro_align:
try:
nucl_id = corr_dict[pro_rec.id]
except KeyError:
print("Protein record (%s) is not in corr_dict!" % pro_rec.id)
exit(1)
pro_nucl_pair.append((pro_rec, nucl_seqs[nucl_id]))
codon_aln = []
shift = False
for pair in pro_nucl_pair:
# Beware that the following span corresponds to an ungapped
# nucleotide sequence.
corr_span = _check_corr(
pair[0],
pair[1],
gap_char=gap_char,
codon_table=codon_table,
complete_protein=complete_protein,
anchor_len=anchor_len,
)
if not corr_span:
raise ValueError(f"Protein Record {pair[0].id} and "
f"Nucleotide Record {pair[1].id} do not match!")
else:
codon_rec = _get_codon_rec(
pair[0],
pair[1],
corr_span,
alphabet=alphabet,
complete_protein=False,
codon_table=codon_table,
max_score=max_score,
)
codon_aln.append(codon_rec)
if corr_span[1] == 2:
shift = True
if shift:
return CodonAlignment(_align_shift_recs(codon_aln), alphabet=alphabet)
else:
return CodonAlignment(codon_aln, alphabet=alphabet)