def PhdIterator(handle):
"""Returns SeqRecord objects from a PHD file.
This uses the Bio.Sequencing.Phd module to do the hard work.
"""
phd_records = Phd.parse(handle)
for phd_record in phd_records:
#Convert the PHY record into a SeqRecord...
#The "filename" can contain spaces, e.g. 'HWI-EAS94_4_1_1_602_99 1'
#from unit test example file phd_solexa.
#This will cause problems if used as the record identifier
#(e.g. output for FASTQ format).
name = phd_record.file_name.split(None, 1)[0]
seq_record = SeqRecord(phd_record.seq,
id=name, name=name,
description=phd_record.file_name)
#Just re-use the comments dictionary as the SeqRecord's annotations
seq_record.annotations = phd_record.comments
#And store the qualities and peak locations as per-letter-annotation
seq_record.letter_annotations["phred_quality"] = \
[int(site[1]) for site in phd_record.sites]
try:
seq_record.letter_annotations["peak_location"] = \
[int(site[2]) for site in phd_record.sites]
except IndexError:
# peak locations are not always there according to
# David Gordon (the Consed author)
pass
yield seq_record
def PhdIterator(handle):
"""Returns SeqRecord objects from a PHD file.
This uses the Bio.Sequencing.Phd module to do the hard work.
"""
phd_records = Phd.parse(handle)
for phd_record in phd_records:
#Convert the PHY record into a SeqRecord...
#The "filename" can contain spaces, e.g. 'HWI-EAS94_4_1_1_602_99 1'
#from unit test example file phd_solexa.
#This will cause problems if used as the record identifier
#(e.g. output for FASTQ format).
name = phd_record.file_name.split(None, 1)[0]
seq_record = SeqRecord(phd_record.seq,
id=name,
name=name,
description=phd_record.file_name)
#Just re-use the comments dictionary as the SeqRecord's annotations
seq_record.annotations = phd_record.comments
#And store the qualities and peak locations as per-letter-annotation
seq_record.letter_annotations["phred_quality"] = \
[int(site[1]) for site in phd_record.sites]
try:
seq_record.letter_annotations["peak_location"] = \
[int(site[2]) for site in phd_record.sites]
except IndexError:
# peak locations are not always there according to
# David Gordon (the Consed author)
pass
yield seq_record
def to_seqrecord(self):
"""Create a SeqRecord object from this Sequence instance.
The seqrecord.annotations dictionary is packed like so::
{ # Sequence attributes with no SeqRecord equivalent:
'id_ref': self.id_ref,
'id_source': self.id_source,
'location': self.location,
'uri': { 'value': self.uri.value,
'desc': self.uri.desc,
'type': self.uri.type },
# Sequence.annotations attribute (list of Annotations)
'annotations': [{ 'ref': ann.ref,
'source': ann.source,
'evidence': ann.evidence,
'type': ann.type,
'confidence': [ ann.confidence.value,
ann.confidence.type ],
'properties': [{ 'value': prop.value,
'ref': prop.ref,
'applies_to': prop.applies_to,
'datatype': prop.datatype,
'unit': prop.unit,
'id_ref': prop.id_ref }
for prop in ann.properties],
} for ann in self.annotations],
}
"""
def clean_dict(dct):
"""Remove None-valued items from a dictionary."""
return dict(
(key, val) for key, val in dct.items() if val is not None)
seqrec = SeqRecord(
Seq(self.mol_seq.value, self.get_alphabet()),
**clean_dict({
'id': str(self.accession),
'name': self.symbol,
'description': self.name,
# 'dbxrefs': None,
}))
if self.domain_architecture:
seqrec.features = [
dom.to_seqfeature() for dom in self.domain_architecture.domains
]
# Sequence attributes with no SeqRecord equivalent
seqrec.annotations = clean_dict({
'id_ref':
self.id_ref,
'id_source':
self.id_source,
'location':
self.location,
'uri':
self.uri and clean_dict({
'value': self.uri.value,
'desc': self.uri.desc,
'type': self.uri.type,
}),
'annotations':
self.annotations and [
clean_dict({
'ref':
ann.ref,
'source':
ann.source,
'evidence':
ann.evidence,
'type':
ann.type,
'confidence':
ann.confidence
and [ann.confidence.value, ann.confidence.type],
'properties': [
clean_dict({
'value': prop.value,
'ref': prop.ref,
'applies_to': prop.applies_to,
'datatype': prop.datatype,
'unit': prop.unit,
'id_ref': prop.id_ref
}) for prop in ann.properties
],
}) for ann in self.annotations
],
})
return seqrec
def PdbSeqresIterator(handle):
"""Returns SeqRecord objects for each chain in a PDB file.
The sequences are derived from the SEQRES lines in the
PDB file header, not the atoms of the 3D structure.
Specifically, these PDB records are handled: DBREF, SEQADV, SEQRES, MODRES
See: http://www.wwpdb.org/documentation/format23/sect3.html
"""
# Late-binding import to avoid circular dependency on SeqIO in Bio.SeqUtils
from SAP.Bio.SeqUtils import seq1
chains = collections.defaultdict(list)
metadata = collections.defaultdict(list)
for line in handle:
rec_name = line[0:6].strip()
if rec_name == 'SEQRES':
# NB: We only actually need chain ID and the residues here;
# commented bits are placeholders from the wwPDB spec.
# Serial number of the SEQRES record for the current chain.
# Starts at 1 and increments by one each line.
# Reset to 1 for each chain.
# ser_num = int(line[8:10])
# Chain identifier. This may be any single legal character,
# including a blank which is used if there is only one chain.
chn_id = line[11]
# Number of residues in the chain (repeated on every record)
# num_res = int(line[13:17])
residues = [
seq1(res, custom_map=protein_letters_3to1)
for res in line[19:].split()
]
chains[chn_id].extend(residues)
elif rec_name == 'DBREF':
# ID code of this entry (PDB ID)
pdb_id = line[7:11]
# Chain identifier.
chn_id = line[12]
# Initial sequence number of the PDB sequence segment.
# seq_begin = int(line[14:18])
# Initial insertion code of the PDB sequence segment.
# icode_begin = line[18]
# Ending sequence number of the PDB sequence segment.
# seq_end = int(line[20:24])
# Ending insertion code of the PDB sequence segment.
# icode_end = line[24]
# Sequence database name.
database = line[26:32].strip()
# Sequence database accession code.
db_acc = line[33:41].strip()
# Sequence database identification code.
db_id_code = line[42:54].strip()
# Initial sequence number of the database seqment.
# db_seq_begin = int(line[55:60])
# Insertion code of initial residue of the segment, if PDB is the
# reference.
# db_icode_begin = line[60]
# Ending sequence number of the database segment.
# db_seq_end = int(line[62:67])
# Insertion code of the ending residue of the segment, if PDB is the
# reference.
# db_icode_end = line[67]
metadata[chn_id].append({
'pdb_id': pdb_id,
'database': database,
'db_acc': db_acc,
'db_id_code': db_id_code
})
# ENH: 'SEQADV' 'MODRES'
for chn_id, residues in sorted(chains.items()):
record = SeqRecord(Seq(''.join(residues), generic_protein))
record.annotations = {"chain": chn_id}
if chn_id in metadata:
m = metadata[chn_id][0]
record.id = record.name = "%s:%s" % (m['pdb_id'], chn_id)
record.description = (
"%s:%s %s" % (m['database'], m['db_acc'], m['db_id_code']))
for melem in metadata[chn_id]:
record.dbxrefs.extend([
"%s:%s" % (melem['database'], melem['db_acc']),
"%s:%s" % (melem['database'], melem['db_id_code'])
])
else:
record.id = chn_id
yield record
def PdbAtomIterator(handle):
"""Returns SeqRecord objects for each chain in a PDB file
The sequences are derived from the 3D structure (ATOM records), not the
SEQRES lines in the PDB file header.
Unrecognised three letter amino acid codes (e.g. "CSD") from HETATM entries
are converted to "X" in the sequence.
In addition to information from the PDB header (which is the same for all
records), the following chain specific information is placed in the
annotation:
record.annotations["residues"] = List of residue ID strings
record.annotations["chain"] = Chain ID (typically A, B ,...)
record.annotations["model"] = Model ID (typically zero)
Where amino acids are missing from the structure, as indicated by residue
numbering, the sequence is filled in with 'X' characters to match the size
of the missing region, and None is included as the corresponding entry in
the list record.annotations["residues"].
This function uses the Bio.PDB module to do most of the hard work. The
annotation information could be improved but this extra parsing should be
done in parse_pdb_header, not this module.
"""
# Only import PDB when needed, to avoid/delay NumPy dependency in SeqIO
from SAP.Bio.PDB import PDBParser
from SAP.Bio.SeqUtils import seq1
def restype(residue):
"""Return a residue's type as a one-letter code.
Non-standard residues (e.g. CSD, ANP) are returned as 'X'.
"""
return seq1(residue.resname, custom_map=protein_letters_3to1)
# Deduce the PDB ID from the PDB header
# ENH: or filename?
from SAP.Bio.File import UndoHandle
undo_handle = UndoHandle(handle)
firstline = undo_handle.peekline()
if firstline.startswith("HEADER"):
pdb_id = firstline[62:66]
else:
warnings.warn("First line is not a 'HEADER'; can't determine PDB ID")
pdb_id = '????'
struct = PDBParser().get_structure(pdb_id, undo_handle)
model = struct[0]
for chn_id, chain in sorted(model.child_dict.items()):
# HETATM mod. res. policy: remove mod if in sequence, else discard
residues = [
res for res in chain.get_unpacked_list()
if seq1(res.get_resname().upper(), custom_map=protein_letters_3to1)
!= "X"
]
if not residues:
continue
# Identify missing residues in the structure
# (fill the sequence with 'X' residues in these regions)
gaps = []
rnumbers = [r.id[1] for r in residues]
for i, rnum in enumerate(rnumbers[:-1]):
if rnumbers[i + 1] != rnum + 1:
# It's a gap!
gaps.append((i + 1, rnum, rnumbers[i + 1]))
if gaps:
res_out = []
prev_idx = 0
for i, pregap, postgap in gaps:
if postgap > pregap:
gapsize = postgap - pregap - 1
res_out.extend(restype(x) for x in residues[prev_idx:i])
prev_idx = i
res_out.append('X' * gapsize)
else:
warnings.warn("Ignoring out-of-order residues after a gap",
UserWarning)
# Keep the normal part, drop the out-of-order segment
# (presumably modified or hetatm residues, e.g. 3BEG)
res_out.extend(restype(x) for x in residues[prev_idx:i])
break
else:
# Last segment
res_out.extend(restype(x) for x in residues[prev_idx:])
else:
# No gaps
res_out = [restype(x) for x in residues]
record_id = "%s:%s" % (pdb_id, chn_id)
# ENH - model number in SeqRecord id if multiple models?
# id = "Chain%s" % str(chain.id)
# if len(structure) > 1 :
# id = ("Model%s|" % str(model.id)) + id
record = SeqRecord(
Seq(''.join(res_out), generic_protein),
id=record_id,
description=record_id,
)
# The PDB header was loaded as a dictionary, so let's reuse it all
record.annotations = struct.header.copy()
# Plus some chain specifics:
record.annotations["model"] = model.id
record.annotations["chain"] = chain.id
# Start & end
record.annotations["start"] = int(rnumbers[0])
record.annotations["end"] = int(rnumbers[-1])
# ENH - add letter annotations -- per-residue info, e.g. numbers
yield record
def to_seqrecord(self):
"""Create a SeqRecord object from this Sequence instance.
The seqrecord.annotations dictionary is packed like so::
{ # Sequence attributes with no SeqRecord equivalent:
'id_ref': self.id_ref,
'id_source': self.id_source,
'location': self.location,
'uri': { 'value': self.uri.value,
'desc': self.uri.desc,
'type': self.uri.type },
# Sequence.annotations attribute (list of Annotations)
'annotations': [{ 'ref': ann.ref,
'source': ann.source,
'evidence': ann.evidence,
'type': ann.type,
'confidence': [ ann.confidence.value,
ann.confidence.type ],
'properties': [{ 'value': prop.value,
'ref': prop.ref,
'applies_to': prop.applies_to,
'datatype': prop.datatype,
'unit': prop.unit,
'id_ref': prop.id_ref }
for prop in ann.properties],
} for ann in self.annotations],
}
"""
def clean_dict(dct):
"""Remove None-valued items from a dictionary."""
return dict((key, val) for key, val in dct.items()
if val is not None)
seqrec = SeqRecord(Seq(self.mol_seq.value, self.get_alphabet()),
**clean_dict({
'id': str(self.accession),
'name': self.symbol,
'description': self.name,
# 'dbxrefs': None,
}))
if self.domain_architecture:
seqrec.features = [dom.to_seqfeature()
for dom in self.domain_architecture.domains]
# Sequence attributes with no SeqRecord equivalent
seqrec.annotations = clean_dict({
'id_ref': self.id_ref,
'id_source': self.id_source,
'location': self.location,
'uri': self.uri and clean_dict({
'value': self.uri.value,
'desc': self.uri.desc,
'type': self.uri.type,
}),
'annotations': self.annotations and [
clean_dict({
'ref': ann.ref,
'source': ann.source,
'evidence': ann.evidence,
'type': ann.type,
'confidence': ann.confidence and [
ann.confidence.value,
ann.confidence.type],
'properties': [clean_dict({
'value': prop.value,
'ref': prop.ref,
'applies_to': prop.applies_to,
'datatype': prop.datatype,
'unit': prop.unit,
'id_ref': prop.id_ref })
for prop in ann.properties],
}) for ann in self.annotations],
})
return seqrec
def PdbAtomIterator(handle):
"""Returns SeqRecord objects for each chain in a PDB file
The sequences are derived from the 3D structure (ATOM records), not the
SEQRES lines in the PDB file header.
Unrecognised three letter amino acid codes (e.g. "CSD") from HETATM entries
are converted to "X" in the sequence.
In addition to information from the PDB header (which is the same for all
records), the following chain specific information is placed in the
annotation:
record.annotations["residues"] = List of residue ID strings
record.annotations["chain"] = Chain ID (typically A, B ,...)
record.annotations["model"] = Model ID (typically zero)
Where amino acids are missing from the structure, as indicated by residue
numbering, the sequence is filled in with 'X' characters to match the size
of the missing region, and None is included as the corresponding entry in
the list record.annotations["residues"].
This function uses the Bio.PDB module to do most of the hard work. The
annotation information could be improved but this extra parsing should be
done in parse_pdb_header, not this module.
"""
# Only import PDB when needed, to avoid/delay NumPy dependency in SeqIO
from SAP.Bio.PDB import PDBParser
from SAP.Bio.SeqUtils import seq1
def restype(residue):
"""Return a residue's type as a one-letter code.
Non-standard residues (e.g. CSD, ANP) are returned as 'X'.
"""
return seq1(residue.resname, custom_map=protein_letters_3to1)
# Deduce the PDB ID from the PDB header
# ENH: or filename?
from SAP.Bio.File import UndoHandle
undo_handle = UndoHandle(handle)
firstline = undo_handle.peekline()
if firstline.startswith("HEADER"):
pdb_id = firstline[62:66]
else:
warnings.warn("First line is not a 'HEADER'; can't determine PDB ID")
pdb_id = '????'
struct = PDBParser().get_structure(pdb_id, undo_handle)
model = struct[0]
for chn_id, chain in sorted(model.child_dict.items()):
# HETATM mod. res. policy: remove mod if in sequence, else discard
residues = [res for res in chain.get_unpacked_list()
if seq1(res.get_resname().upper(),
custom_map=protein_letters_3to1) != "X"]
if not residues:
continue
# Identify missing residues in the structure
# (fill the sequence with 'X' residues in these regions)
gaps = []
rnumbers = [r.id[1] for r in residues]
for i, rnum in enumerate(rnumbers[:-1]):
if rnumbers[i+1] != rnum + 1:
# It's a gap!
gaps.append((i+1, rnum, rnumbers[i+1]))
if gaps:
res_out = []
prev_idx = 0
for i, pregap, postgap in gaps:
if postgap > pregap:
gapsize = postgap - pregap - 1
res_out.extend(restype(x) for x in residues[prev_idx:i])
prev_idx = i
res_out.append('X'*gapsize)
else:
warnings.warn("Ignoring out-of-order residues after a gap",
UserWarning)
# Keep the normal part, drop the out-of-order segment
# (presumably modified or hetatm residues, e.g. 3BEG)
res_out.extend(restype(x) for x in residues[prev_idx:i])
break
else:
# Last segment
res_out.extend(restype(x) for x in residues[prev_idx:])
else:
# No gaps
res_out = [restype(x) for x in residues]
record_id = "%s:%s" % (pdb_id, chn_id)
# ENH - model number in SeqRecord id if multiple models?
# id = "Chain%s" % str(chain.id)
# if len(structure) > 1 :
# id = ("Model%s|" % str(model.id)) + id
record = SeqRecord(Seq(''.join(res_out), generic_protein),
id=record_id,
description=record_id,
)
# The PDB header was loaded as a dictionary, so let's reuse it all
record.annotations = struct.header.copy()
# Plus some chain specifics:
record.annotations["model"] = model.id
record.annotations["chain"] = chain.id
# Start & end
record.annotations["start"] = int(rnumbers[0])
record.annotations["end"] = int(rnumbers[-1])
# ENH - add letter annotations -- per-residue info, e.g. numbers
yield record
def PdbSeqresIterator(handle):
"""Returns SeqRecord objects for each chain in a PDB file.
The sequences are derived from the SEQRES lines in the
PDB file header, not the atoms of the 3D structure.
Specifically, these PDB records are handled: DBREF, SEQADV, SEQRES, MODRES
See: http://www.wwpdb.org/documentation/format23/sect3.html
"""
# Late-binding import to avoid circular dependency on SeqIO in Bio.SeqUtils
from SAP.Bio.SeqUtils import seq1
chains = collections.defaultdict(list)
metadata = collections.defaultdict(list)
for line in handle:
rec_name = line[0:6].strip()
if rec_name == 'SEQRES':
# NB: We only actually need chain ID and the residues here;
# commented bits are placeholders from the wwPDB spec.
# Serial number of the SEQRES record for the current chain.
# Starts at 1 and increments by one each line.
# Reset to 1 for each chain.
# ser_num = int(line[8:10])
# Chain identifier. This may be any single legal character,
# including a blank which is used if there is only one chain.
chn_id = line[11]
# Number of residues in the chain (repeated on every record)
# num_res = int(line[13:17])
residues = [seq1(res, custom_map=protein_letters_3to1) for res in line[19:].split()]
chains[chn_id].extend(residues)
elif rec_name == 'DBREF':
# ID code of this entry (PDB ID)
pdb_id = line[7:11]
# Chain identifier.
chn_id = line[12]
# Initial sequence number of the PDB sequence segment.
# seq_begin = int(line[14:18])
# Initial insertion code of the PDB sequence segment.
# icode_begin = line[18]
# Ending sequence number of the PDB sequence segment.
# seq_end = int(line[20:24])
# Ending insertion code of the PDB sequence segment.
# icode_end = line[24]
# Sequence database name.
database = line[26:32].strip()
# Sequence database accession code.
db_acc = line[33:41].strip()
# Sequence database identification code.
db_id_code = line[42:54].strip()
# Initial sequence number of the database seqment.
# db_seq_begin = int(line[55:60])
# Insertion code of initial residue of the segment, if PDB is the
# reference.
# db_icode_begin = line[60]
# Ending sequence number of the database segment.
# db_seq_end = int(line[62:67])
# Insertion code of the ending residue of the segment, if PDB is the
# reference.
# db_icode_end = line[67]
metadata[chn_id].append({'pdb_id': pdb_id, 'database': database,
'db_acc': db_acc, 'db_id_code': db_id_code})
# ENH: 'SEQADV' 'MODRES'
for chn_id, residues in sorted(chains.items()):
record = SeqRecord(Seq(''.join(residues), generic_protein))
record.annotations = {"chain": chn_id}
if chn_id in metadata:
m = metadata[chn_id][0]
record.id = record.name = "%s:%s" % (m['pdb_id'], chn_id)
record.description = ("%s:%s %s" % (m['database'],
m['db_acc'],
m['db_id_code']))
for melem in metadata[chn_id]:
record.dbxrefs.extend([
"%s:%s" % (melem['database'], melem['db_acc']),
"%s:%s" % (melem['database'], melem['db_id_code'])])
else:
record.id = chn_id
yield record
