def __init__(self, PERMISSIVE=True, get_header=False,
structure_builder=None, QUIET=False):
"""
The PDB parser call a number of standard methods in an aggregated
StructureBuilder object. Normally this object is instanciated by the
PDBParser object itself, but if the user provides his/her own
StructureBuilder object, the latter is used instead.
Arguments:
o PERMISSIVE - Evaluated as a Boolean. If false, exceptions in
constructing the SMCRA data structure are fatal. If true (DEFAULT),
the exceptions are caught, but some residues or atoms will be missing.
THESE EXCEPTIONS ARE DUE TO PROBLEMS IN THE PDB FILE!.
o structure_builder - an optional user implemented StructureBuilder class.
o QUIET - Evaluated as a Boolean. If true, warnings issued in constructing
the SMCRA data will be suppressed. If false (DEFAULT), they will be shown.
These warnings might be indicative of problems in the PDB file!
"""
if structure_builder is not None:
self.structure_builder = structure_builder
else:
self.structure_builder = StructureBuilder()
self.header = None
self.trailer = None
self.line_counter = 0
self.PERMISSIVE = bool(PERMISSIVE)
self.QUIET = bool(QUIET)
def __init__(self, PERMISSIVE=True, get_header=False, structure_builder=None, QUIET=False):
"""
The PDB parser call a number of standard methods in an aggregated
StructureBuilder object. Normally this object is instanciated by the
PDBParser object itself, but if the user provides his/her own
StructureBuilder object, the latter is used instead.
Arguments:
o PERMISSIVE - Evaluated as a Boolean. If false, exceptions in
constructing the SMCRA data structure are fatal. If true (DEFAULT),
the exceptions are caught, but some residues or atoms will be missing.
THESE EXCEPTIONS ARE DUE TO PROBLEMS IN THE PDB FILE!.
o structure_builder - an optional user implemented StructureBuilder class.
o QUIET - Evaluated as a Boolean. If true, warnings issued in constructing
the SMCRA data will be suppressed. If false (DEFAULT), they will be shown.
These warnings might be indicative of problems in the PDB file!
"""
if structure_builder is not None:
self.structure_builder = structure_builder
else:
self.structure_builder = StructureBuilder()
self.header = None
self.trailer = None
self.line_counter = 0
self.PERMISSIVE = bool(PERMISSIVE)
self.QUIET = bool(QUIET)
def set_structure(self, pdb_object):
# Check what the user is providing and build a structure appropriately
if pdb_object.level == "S":
structure = pdb_object
else:
sb = StructureBuilder()
sb.init_structure('pdb')
sb.init_seg(' ')
# Build parts as necessary
if pdb_object.level == "M":
sb.structure.add(pdb_object)
self.structure = sb.structure
else:
sb.init_model(0)
if pdb_object.level == "C":
sb.structure[0].add(pdb_object)
else:
sb.init_chain('A')
if pdb_object.level == "R":
try:
parent_id = pdb_object.parent.id
sb.structure[0]['A'].id = parent_id
except Exception:
pass
sb.structure[0]['A'].add(pdb_object)
else:
# Atom
sb.init_residue('DUM', ' ', 1, ' ')
try:
parent_id = pdb_object.parent.parent.id
sb.structure[0]['A'].id = parent_id
except Exception:
pass
sb.structure[0]['A'].child_list[0].add(pdb_object)
# Return structure
structure = sb.structure
self.structure=structure
class PDBParser(object):
"""
Parse a PDB file and return a Structure object.
"""
def __init__(self, PERMISSIVE=True, get_header=False, structure_builder=None, QUIET=False):
"""
The PDB parser call a number of standard methods in an aggregated
StructureBuilder object. Normally this object is instanciated by the
PDBParser object itself, but if the user provides his/her own
StructureBuilder object, the latter is used instead.
Arguments:
o PERMISSIVE - Evaluated as a Boolean. If false, exceptions in
constructing the SMCRA data structure are fatal. If true (DEFAULT),
the exceptions are caught, but some residues or atoms will be missing.
THESE EXCEPTIONS ARE DUE TO PROBLEMS IN THE PDB FILE!.
o structure_builder - an optional user implemented StructureBuilder class.
o QUIET - Evaluated as a Boolean. If true, warnings issued in constructing
the SMCRA data will be suppressed. If false (DEFAULT), they will be shown.
These warnings might be indicative of problems in the PDB file!
"""
if structure_builder is not None:
self.structure_builder = structure_builder
else:
self.structure_builder = StructureBuilder()
self.header = None
self.trailer = None
self.line_counter = 0
self.PERMISSIVE = bool(PERMISSIVE)
self.QUIET = bool(QUIET)
# Public methods
def get_structure(self, id, file):
"""Return the structure.
Arguments:
o id - string, the id that will be used for the structure
o file - name of the PDB file OR an open filehandle
"""
with warnings.catch_warnings():
if self.QUIET:
warnings.filterwarnings("ignore", category=PDBConstructionWarning)
self.header = None
self.trailer = None
# Make a StructureBuilder instance (pass id of structure as parameter)
self.structure_builder.init_structure(id)
with as_handle(file) as handle:
self._parse(handle.readlines())
self.structure_builder.set_header(self.header)
# Return the Structure instance
structure = self.structure_builder.get_structure()
return structure
def get_header(self):
"Return the header."
return self.header
def get_trailer(self):
"Return the trailer."
return self.trailer
# Private methods
def _parse(self, header_coords_trailer):
"Parse the PDB file."
# Extract the header; return the rest of the file
self.header, coords_trailer = self._get_header(header_coords_trailer)
# Parse the atomic data; return the PDB file trailer
self.trailer = self._parse_coordinates(coords_trailer)
def _get_header(self, header_coords_trailer):
"Get the header of the PDB file, return the rest."
structure_builder = self.structure_builder
i = 0
for i in range(0, len(header_coords_trailer)):
structure_builder.set_line_counter(i + 1)
line = header_coords_trailer[i]
record_type = line[0:6]
if record_type == "ATOM " or record_type == "HETATM" or record_type == "MODEL ":
break
header = header_coords_trailer[0:i]
# Return the rest of the coords+trailer for further processing
self.line_counter = i
coords_trailer = header_coords_trailer[i:]
header_dict = _parse_pdb_header_list(header)
return header_dict, coords_trailer
def _parse_coordinates(self, coords_trailer):
"Parse the atomic data in the PDB file."
local_line_counter = 0
structure_builder = self.structure_builder
current_model_id = 0
# Flag we have an open model
model_open = 0
current_chain_id = None
current_segid = None
current_residue_id = None
current_resname = None
for i in range(0, len(coords_trailer)):
line = coords_trailer[i]
record_type = line[0:6]
global_line_counter = self.line_counter + local_line_counter + 1
structure_builder.set_line_counter(global_line_counter)
if record_type == "ATOM " or record_type == "HETATM":
# Initialize the Model - there was no explicit MODEL record
if not model_open:
structure_builder.init_model(current_model_id)
current_model_id += 1
model_open = 1
fullname = line[12:16]
# get rid of whitespace in atom names
split_list = fullname.split()
if len(split_list) != 1:
# atom name has internal spaces, e.g. " N B ", so
# we do not strip spaces
name = fullname
else:
# atom name is like " CA ", so we can strip spaces
name = split_list[0]
altloc = line[16]
resname = line[17:20]
chainid = line[21]
try:
serial_number = int(line[6:11])
except:
serial_number = 0
resseq = int(line[22:26].split()[0]) # sequence identifier
icode = line[26] # insertion code
if record_type == "HETATM": # hetero atom flag
if resname == "HOH" or resname == "WAT":
hetero_flag = "W"
else:
hetero_flag = "H"
else:
hetero_flag = " "
residue_id = (hetero_flag, resseq, icode)
# atomic coordinates
try:
x = float(line[30:38])
y = float(line[38:46])
z = float(line[46:54])
except:
# Should we allow parsing to continue in permissive mode?
# If so, what coordinates should we default to? Easier to abort!
raise PDBConstructionException("Invalid or missing coordinate(s) at line %i." % global_line_counter)
coord = numpy.array((x, y, z), "f")
# occupancy & B factor
try:
occupancy = float(line[54:60])
except:
self._handle_PDB_exception("Invalid or missing occupancy", global_line_counter)
occupancy = None # Rather than arbitrary zero or one
try:
bfactor = float(line[60:66])
except:
self._handle_PDB_exception("Invalid or missing B factor", global_line_counter)
bfactor = 0.0 # The PDB use a default of zero if the data is missing
segid = line[72:76]
element = line[76:78].strip()
if current_segid != segid:
current_segid = segid
structure_builder.init_seg(current_segid)
if current_chain_id != chainid:
current_chain_id = chainid
structure_builder.init_chain(current_chain_id)
current_residue_id = residue_id
current_resname = resname
try:
structure_builder.init_residue(resname, hetero_flag, resseq, icode)
except PDBConstructionException as message:
self._handle_PDB_exception(message, global_line_counter)
elif current_residue_id != residue_id or current_resname != resname:
current_residue_id = residue_id
current_resname = resname
try:
structure_builder.init_residue(resname, hetero_flag, resseq, icode)
except PDBConstructionException as message:
self._handle_PDB_exception(message, global_line_counter)
# init atom
try:
structure_builder.init_atom(
name, coord, bfactor, occupancy, altloc, fullname, serial_number, element
)
except PDBConstructionException as message:
self._handle_PDB_exception(message, global_line_counter)
elif record_type == "ANISOU":
anisou = [
float(x) for x in (line[28:35], line[35:42], line[43:49], line[49:56], line[56:63], line[63:70])
]
# U's are scaled by 10^4
anisou_array = (numpy.array(anisou, "f") / 10000.0).astype("f")
structure_builder.set_anisou(anisou_array)
elif record_type == "MODEL ":
try:
serial_num = int(line[10:14])
except:
self._handle_PDB_exception("Invalid or missing model serial number", global_line_counter)
serial_num = 0
structure_builder.init_model(current_model_id, serial_num)
current_model_id += 1
model_open = 1
current_chain_id = None
current_residue_id = None
elif record_type == "END " or record_type == "CONECT":
# End of atomic data, return the trailer
self.line_counter += local_line_counter
return coords_trailer[local_line_counter:]
elif record_type == "ENDMDL":
model_open = 0
current_chain_id = None
current_residue_id = None
elif record_type == "SIGUIJ":
# standard deviation of anisotropic B factor
siguij = [
float(x) for x in (line[28:35], line[35:42], line[42:49], line[49:56], line[56:63], line[63:70])
]
# U sigma's are scaled by 10^4
siguij_array = (numpy.array(siguij, "f") / 10000.0).astype("f")
structure_builder.set_siguij(siguij_array)
elif record_type == "SIGATM":
# standard deviation of atomic positions
sigatm = [float(x) for x in (line[30:38], line[38:45], line[46:54], line[54:60], line[60:66])]
sigatm_array = numpy.array(sigatm, "f")
structure_builder.set_sigatm(sigatm_array)
local_line_counter += 1
# EOF (does not end in END or CONECT)
self.line_counter = self.line_counter + local_line_counter
return []
def _handle_PDB_exception(self, message, line_counter):
"""
This method catches an exception that occurs in the StructureBuilder
object (if PERMISSIVE), or raises it again, this time adding the
PDB line number to the error message.
"""
message = "%s at line %i." % (message, line_counter)
if self.PERMISSIVE:
# just print a warning - some residues/atoms may be missing
warnings.warn(
"PDBConstructionException: %s\n"
"Exception ignored.\n"
"Some atoms or residues may be missing in the data structure." % message,
PDBConstructionWarning,
)
else:
# exceptions are fatal - raise again with new message (including line nr)
raise PDBConstructionException(message)
def get_structure(self, structure_id, filename):
self._mmcif_dict = MMCIF2Dict(filename)
self._structure_builder = StructureBuilder()
self._build_structure(structure_id)
return self._structure_builder.get_structure()
class MMCIFParser(object):
def get_structure(self, structure_id, filename):
self._mmcif_dict = MMCIF2Dict(filename)
self._structure_builder = StructureBuilder()
self._build_structure(structure_id)
return self._structure_builder.get_structure()
def _build_structure(self, structure_id):
mmcif_dict = self._mmcif_dict
atom_id_list = mmcif_dict["_atom_site.label_atom_id"]
residue_id_list = mmcif_dict["_atom_site.label_comp_id"]
try:
element_list = mmcif_dict["_atom_site.type_symbol"]
except KeyError:
element_list = None
seq_id_list = mmcif_dict["_atom_site.label_seq_id"]
chain_id_list = mmcif_dict["_atom_site.label_asym_id"]
x_list = [float(x) for x in mmcif_dict["_atom_site.Cartn_x"]]
y_list = [float(x) for x in mmcif_dict["_atom_site.Cartn_y"]]
z_list = [float(x) for x in mmcif_dict["_atom_site.Cartn_z"]]
alt_list = mmcif_dict["_atom_site.label_alt_id"]
b_factor_list = mmcif_dict["_atom_site.B_iso_or_equiv"]
occupancy_list = mmcif_dict["_atom_site.occupancy"]
fieldname_list = mmcif_dict["_atom_site.group_PDB"]
try:
serial_list = [
int(n) for n in mmcif_dict["_atom_site.pdbx_PDB_model_num"]
]
except KeyError:
# No model number column
serial_list = None
except ValueError:
# Invalid model number (malformed file)
raise PDBConstructionException("Invalid model number")
try:
aniso_u11 = mmcif_dict["_atom_site.aniso_U[1][1]"]
aniso_u12 = mmcif_dict["_atom_site.aniso_U[1][2]"]
aniso_u13 = mmcif_dict["_atom_site.aniso_U[1][3]"]
aniso_u22 = mmcif_dict["_atom_site.aniso_U[2][2]"]
aniso_u23 = mmcif_dict["_atom_site.aniso_U[2][3]"]
aniso_u33 = mmcif_dict["_atom_site.aniso_U[3][3]"]
aniso_flag = 1
except KeyError:
# no anisotropic B factors
aniso_flag = 0
# if auth_seq_id is present, we use this.
# Otherwise label_seq_id is used.
if "_atom_site.auth_seq_id" in mmcif_dict:
seq_id_list = mmcif_dict["_atom_site.auth_seq_id"]
else:
seq_id_list = mmcif_dict["_atom_site.label_seq_id"]
# Now loop over atoms and build the structure
current_chain_id = None
current_residue_id = None
structure_builder = self._structure_builder
structure_builder.init_structure(structure_id)
structure_builder.init_seg(" ")
# Historically, Biopython PDB parser uses model_id to mean array index
# so serial_id means the Model ID specified in the file
current_model_id = 0
current_serial_id = 0
for i in range(0, len(atom_id_list)):
x = x_list[i]
y = y_list[i]
z = z_list[i]
resname = residue_id_list[i]
chainid = chain_id_list[i]
altloc = alt_list[i]
if altloc == ".":
altloc = " "
resseq = seq_id_list[i]
name = atom_id_list[i]
# occupancy & B factor
try:
tempfactor = float(b_factor_list[i])
except ValueError:
raise PDBConstructionException("Invalid or missing B factor")
try:
occupancy = float(occupancy_list[i])
except ValueError:
raise PDBConstructionException("Invalid or missing occupancy")
fieldname = fieldname_list[i]
if fieldname == "HETATM":
hetatm_flag = "H"
else:
hetatm_flag = " "
if serial_list is not None:
# model column exists; use it
serial_id = serial_list[i]
if current_serial_id != serial_id:
# if serial changes, update it and start new model
current_serial_id = serial_id
structure_builder.init_model(current_model_id,
current_serial_id)
current_model_id += 1
else:
# no explicit model column; initialize single model
structure_builder.init_model(current_model_id)
if current_chain_id != chainid:
current_chain_id = chainid
structure_builder.init_chain(current_chain_id)
current_residue_id = resseq
icode, int_resseq = self._get_icode(resseq)
structure_builder.init_residue(resname, hetatm_flag,
int_resseq, icode)
elif current_residue_id != resseq:
current_residue_id = resseq
icode, int_resseq = self._get_icode(resseq)
structure_builder.init_residue(resname, hetatm_flag,
int_resseq, icode)
coord = numpy.array((x, y, z), 'f')
element = element_list[i] if element_list else None
structure_builder.init_atom(name,
coord,
tempfactor,
occupancy,
altloc,
name,
element=element)
if aniso_flag == 1:
u = (aniso_u11[i], aniso_u12[i], aniso_u13[i], aniso_u22[i],
aniso_u23[i], aniso_u33[i])
mapped_anisou = [float(x) for x in u]
anisou_array = numpy.array(mapped_anisou, 'f')
structure_builder.set_anisou(anisou_array)
# Now try to set the cell
try:
a = float(mmcif_dict["_cell.length_a"])
b = float(mmcif_dict["_cell.length_b"])
c = float(mmcif_dict["_cell.length_c"])
alpha = float(mmcif_dict["_cell.angle_alpha"])
beta = float(mmcif_dict["_cell.angle_beta"])
gamma = float(mmcif_dict["_cell.angle_gamma"])
cell = numpy.array((a, b, c, alpha, beta, gamma), 'f')
spacegroup = mmcif_dict["_symmetry.space_group_name_H-M"]
spacegroup = spacegroup[1:-1] # get rid of quotes!!
if spacegroup is None:
raise Exception
structure_builder.set_symmetry(spacegroup, cell)
except:
pass # no cell found, so just ignore
def _get_icode(self, resseq):
"""Tries to return the icode. In MMCIF files this is just part of
resseq! In PDB files, it's a separate field."""
last_resseq_char = resseq[-1]
if last_resseq_char in ascii_letters:
icode = last_resseq_char
int_resseq = int(resseq[0:-1])
else:
icode = " "
int_resseq = int(resseq)
return icode, int_resseq
def get_structure(self, structure_id, filename):
self._mmcif_dict=MMCIF2Dict(filename)
self._structure_builder=StructureBuilder()
self._build_structure(structure_id)
return self._structure_builder.get_structure()
class MMCIFParser(object):
def get_structure(self, structure_id, filename):
self._mmcif_dict=MMCIF2Dict(filename)
self._structure_builder=StructureBuilder()
self._build_structure(structure_id)
return self._structure_builder.get_structure()
def _build_structure(self, structure_id):
mmcif_dict=self._mmcif_dict
atom_id_list=mmcif_dict["_atom_site.label_atom_id"]
residue_id_list=mmcif_dict["_atom_site.label_comp_id"]
try:
element_list = mmcif_dict["_atom_site.type_symbol"]
except KeyError:
element_list = None
seq_id_list=mmcif_dict["_atom_site.label_seq_id"]
chain_id_list=mmcif_dict["_atom_site.label_asym_id"]
x_list = [float(x) for x in mmcif_dict["_atom_site.Cartn_x"]]
y_list = [float(x) for x in mmcif_dict["_atom_site.Cartn_y"]]
z_list = [float(x) for x in mmcif_dict["_atom_site.Cartn_z"]]
alt_list=mmcif_dict["_atom_site.label_alt_id"]
b_factor_list=mmcif_dict["_atom_site.B_iso_or_equiv"]
occupancy_list=mmcif_dict["_atom_site.occupancy"]
fieldname_list=mmcif_dict["_atom_site.group_PDB"]
try:
serial_list = [int(n) for n in mmcif_dict["_atom_site.pdbx_PDB_model_num"]]
except KeyError:
# No model number column
serial_list = None
except ValueError:
# Invalid model number (malformed file)
raise PDBConstructionException("Invalid model number")
try:
aniso_u11=mmcif_dict["_atom_site.aniso_U[1][1]"]
aniso_u12=mmcif_dict["_atom_site.aniso_U[1][2]"]
aniso_u13=mmcif_dict["_atom_site.aniso_U[1][3]"]
aniso_u22=mmcif_dict["_atom_site.aniso_U[2][2]"]
aniso_u23=mmcif_dict["_atom_site.aniso_U[2][3]"]
aniso_u33=mmcif_dict["_atom_site.aniso_U[3][3]"]
aniso_flag=1
except KeyError:
# no anisotropic B factors
aniso_flag=0
# if auth_seq_id is present, we use this.
# Otherwise label_seq_id is used.
if "_atom_site.auth_seq_id" in mmcif_dict:
seq_id_list=mmcif_dict["_atom_site.auth_seq_id"]
else:
seq_id_list=mmcif_dict["_atom_site.label_seq_id"]
# Now loop over atoms and build the structure
current_chain_id=None
current_residue_id=None
structure_builder=self._structure_builder
structure_builder.init_structure(structure_id)
structure_builder.init_seg(" ")
# Historically, Biopython PDB parser uses model_id to mean array index
# so serial_id means the Model ID specified in the file
current_model_id = 0
current_serial_id = 0
for i in range(0, len(atom_id_list)):
x=x_list[i]
y=y_list[i]
z=z_list[i]
resname=residue_id_list[i]
chainid=chain_id_list[i]
altloc=alt_list[i]
if altloc==".":
altloc=" "
resseq=seq_id_list[i]
name=atom_id_list[i]
# occupancy & B factor
try:
tempfactor=float(b_factor_list[i])
except ValueError:
raise PDBConstructionException("Invalid or missing B factor")
try:
occupancy=float(occupancy_list[i])
except ValueError:
raise PDBConstructionException("Invalid or missing occupancy")
fieldname=fieldname_list[i]
if fieldname=="HETATM":
hetatm_flag="H"
else:
hetatm_flag=" "
if serial_list is not None:
# model column exists; use it
serial_id = serial_list[i]
if current_serial_id != serial_id:
# if serial changes, update it and start new model
current_serial_id = serial_id
structure_builder.init_model(current_model_id, current_serial_id)
current_model_id += 1
else:
# no explicit model column; initialize single model
structure_builder.init_model(current_model_id)
if current_chain_id!=chainid:
current_chain_id=chainid
structure_builder.init_chain(current_chain_id)
current_residue_id=resseq
icode, int_resseq=self._get_icode(resseq)
structure_builder.init_residue(resname, hetatm_flag, int_resseq,
icode)
elif current_residue_id!=resseq:
current_residue_id=resseq
icode, int_resseq=self._get_icode(resseq)
structure_builder.init_residue(resname, hetatm_flag, int_resseq,
icode)
coord=numpy.array((x, y, z), 'f')
element = element_list[i] if element_list else None
structure_builder.init_atom(name, coord, tempfactor, occupancy, altloc,
name, element=element)
if aniso_flag==1:
u=(aniso_u11[i], aniso_u12[i], aniso_u13[i],
aniso_u22[i], aniso_u23[i], aniso_u33[i])
mapped_anisou = [float(x) for x in u]
anisou_array=numpy.array(mapped_anisou, 'f')
structure_builder.set_anisou(anisou_array)
# Now try to set the cell
try:
a=float(mmcif_dict["_cell.length_a"])
b=float(mmcif_dict["_cell.length_b"])
c=float(mmcif_dict["_cell.length_c"])
alpha=float(mmcif_dict["_cell.angle_alpha"])
beta=float(mmcif_dict["_cell.angle_beta"])
gamma=float(mmcif_dict["_cell.angle_gamma"])
cell=numpy.array((a, b, c, alpha, beta, gamma), 'f')
spacegroup=mmcif_dict["_symmetry.space_group_name_H-M"]
spacegroup=spacegroup[1:-1] # get rid of quotes!!
if spacegroup is None:
raise Exception
structure_builder.set_symmetry(spacegroup, cell)
except:
pass # no cell found, so just ignore
def _get_icode(self, resseq):
"""Tries to return the icode. In MMCIF files this is just part of
resseq! In PDB files, it's a separate field."""
last_resseq_char=resseq[-1]
if last_resseq_char in ascii_letters:
icode=last_resseq_char
int_resseq=int(resseq[0:-1])
else:
icode=" "
int_resseq=int(resseq)
return icode, int_resseq
def set_structure(self, pdb_object):
# Check what the user is providing and build a structure appropriately
if pdb_object.level == "S":
structure = pdb_object
else:
sb = StructureBuilder()
sb.init_structure('pdb')
sb.init_seg(' ')
# Build parts as necessary
if pdb_object.level == "M":
sb.structure.add(pdb_object)
self.structure = sb.structure
else:
sb.init_model(0)
if pdb_object.level == "C":
sb.structure[0].add(pdb_object)
else:
sb.init_chain('A')
if pdb_object.level == "R":
try:
parent_id = pdb_object.parent.id
sb.structure[0]['A'].id = parent_id
except Exception:
pass
sb.structure[0]['A'].add(pdb_object)
else:
# Atom
sb.init_residue('DUM', ' ', 1, ' ')
try:
parent_id = pdb_object.parent.parent.id
sb.structure[0]['A'].id = parent_id
except Exception:
pass
sb.structure[0]['A'].child_list[0].add(pdb_object)
# Return structure
structure = sb.structure
self.structure = structure
class PDBParser(object):
"""
Parse a PDB file and return a Structure object.
"""
def __init__(self, PERMISSIVE=True, get_header=False,
structure_builder=None, QUIET=False):
"""
The PDB parser call a number of standard methods in an aggregated
StructureBuilder object. Normally this object is instanciated by the
PDBParser object itself, but if the user provides his/her own
StructureBuilder object, the latter is used instead.
Arguments:
o PERMISSIVE - Evaluated as a Boolean. If false, exceptions in
constructing the SMCRA data structure are fatal. If true (DEFAULT),
the exceptions are caught, but some residues or atoms will be missing.
THESE EXCEPTIONS ARE DUE TO PROBLEMS IN THE PDB FILE!.
o structure_builder - an optional user implemented StructureBuilder class.
o QUIET - Evaluated as a Boolean. If true, warnings issued in constructing
the SMCRA data will be suppressed. If false (DEFAULT), they will be shown.
These warnings might be indicative of problems in the PDB file!
"""
if structure_builder is not None:
self.structure_builder = structure_builder
else:
self.structure_builder = StructureBuilder()
self.header = None
self.trailer = None
self.line_counter = 0
self.PERMISSIVE = bool(PERMISSIVE)
self.QUIET = bool(QUIET)
# Public methods
def get_structure(self, id, file):
"""Return the structure.
Arguments:
o id - string, the id that will be used for the structure
o file - name of the PDB file OR an open filehandle
"""
with warnings.catch_warnings():
if self.QUIET:
warnings.filterwarnings("ignore", category=PDBConstructionWarning)
self.header = None
self.trailer = None
# Make a StructureBuilder instance (pass id of structure as parameter)
self.structure_builder.init_structure(id)
with as_handle(file) as handle:
self._parse(handle.readlines())
self.structure_builder.set_header(self.header)
# Return the Structure instance
structure = self.structure_builder.get_structure()
return structure
def get_header(self):
"Return the header."
return self.header
def get_trailer(self):
"Return the trailer."
return self.trailer
# Private methods
def _parse(self, header_coords_trailer):
"Parse the PDB file."
# Extract the header; return the rest of the file
self.header, coords_trailer = self._get_header(header_coords_trailer)
# Parse the atomic data; return the PDB file trailer
self.trailer = self._parse_coordinates(coords_trailer)
def _get_header(self, header_coords_trailer):
"Get the header of the PDB file, return the rest."
structure_builder = self.structure_builder
i = 0
for i in range(0, len(header_coords_trailer)):
structure_builder.set_line_counter(i + 1)
line = header_coords_trailer[i]
record_type = line[0:6]
if record_type == "ATOM " or record_type == "HETATM" or record_type == "MODEL ":
break
header = header_coords_trailer[0:i]
# Return the rest of the coords+trailer for further processing
self.line_counter = i
coords_trailer = header_coords_trailer[i:]
header_dict = _parse_pdb_header_list(header)
return header_dict, coords_trailer
def _parse_coordinates(self, coords_trailer):
"Parse the atomic data in the PDB file."
local_line_counter = 0
structure_builder = self.structure_builder
current_model_id = 0
# Flag we have an open model
model_open = 0
current_chain_id = None
current_segid = None
current_residue_id = None
current_resname = None
for i in range(0, len(coords_trailer)):
line = coords_trailer[i]
record_type = line[0:6]
global_line_counter = self.line_counter + local_line_counter + 1
structure_builder.set_line_counter(global_line_counter)
if record_type == "ATOM " or record_type == "HETATM":
# Initialize the Model - there was no explicit MODEL record
if not model_open:
structure_builder.init_model(current_model_id)
current_model_id += 1
model_open = 1
fullname = line[12:16]
# get rid of whitespace in atom names
split_list = fullname.split()
if len(split_list) != 1:
# atom name has internal spaces, e.g. " N B ", so
# we do not strip spaces
name = fullname
else:
# atom name is like " CA ", so we can strip spaces
name = split_list[0]
altloc = line[16]
resname = line[17:20]
chainid = line[21]
try:
serial_number = int(line[6:11])
except:
serial_number = 0
resseq = int(line[22:26].split()[0]) # sequence identifier
icode = line[26] # insertion code
if record_type == "HETATM": # hetero atom flag
if resname == "HOH" or resname == "WAT":
hetero_flag = "W"
else:
hetero_flag = "H"
else:
hetero_flag = " "
residue_id = (hetero_flag, resseq, icode)
# atomic coordinates
try:
x = float(line[30:38])
y = float(line[38:46])
z = float(line[46:54])
except:
# Should we allow parsing to continue in permissive mode?
# If so, what coordinates should we default to? Easier to abort!
raise PDBConstructionException("Invalid or missing coordinate(s) at line %i."
% global_line_counter)
coord = numpy.array((x, y, z), "f")
# occupancy & B factor
try:
occupancy = float(line[54:60])
except:
self._handle_PDB_exception("Invalid or missing occupancy",
global_line_counter)
occupancy = None # Rather than arbitrary zero or one
try:
bfactor = float(line[60:66])
except:
self._handle_PDB_exception("Invalid or missing B factor",
global_line_counter)
bfactor = 0.0 # The PDB use a default of zero if the data is missing
segid = line[72:76]
element = line[76:78].strip()
if current_segid != segid:
current_segid = segid
structure_builder.init_seg(current_segid)
if current_chain_id != chainid:
current_chain_id = chainid
structure_builder.init_chain(current_chain_id)
current_residue_id = residue_id
current_resname = resname
try:
structure_builder.init_residue(resname, hetero_flag, resseq, icode)
except PDBConstructionException as message:
self._handle_PDB_exception(message, global_line_counter)
elif current_residue_id != residue_id or current_resname != resname:
current_residue_id = residue_id
current_resname = resname
try:
structure_builder.init_residue(resname, hetero_flag, resseq, icode)
except PDBConstructionException as message:
self._handle_PDB_exception(message, global_line_counter)
# init atom
try:
structure_builder.init_atom(name, coord, bfactor, occupancy, altloc,
fullname, serial_number, element)
except PDBConstructionException as message:
self._handle_PDB_exception(message, global_line_counter)
elif record_type == "ANISOU":
anisou = [float(x) for x in (line[28:35], line[35:42], line[43:49],
line[49:56], line[56:63], line[63:70])]
# U's are scaled by 10^4
anisou_array = (numpy.array(anisou, "f") / 10000.0).astype("f")
structure_builder.set_anisou(anisou_array)
elif record_type == "MODEL ":
try:
serial_num = int(line[10:14])
except:
self._handle_PDB_exception("Invalid or missing model serial number",
global_line_counter)
serial_num = 0
structure_builder.init_model(current_model_id, serial_num)
current_model_id += 1
model_open = 1
current_chain_id = None
current_residue_id = None
elif record_type == "END " or record_type == "CONECT":
# End of atomic data, return the trailer
self.line_counter += local_line_counter
return coords_trailer[local_line_counter:]
elif record_type == "ENDMDL":
model_open = 0
current_chain_id = None
current_residue_id = None
elif record_type == "SIGUIJ":
# standard deviation of anisotropic B factor
siguij = [float(x) for x in (line[28:35], line[35:42], line[42:49],
line[49:56], line[56:63], line[63:70])]
# U sigma's are scaled by 10^4
siguij_array = (numpy.array(siguij, "f") / 10000.0).astype("f")
structure_builder.set_siguij(siguij_array)
elif record_type == "SIGATM":
# standard deviation of atomic positions
sigatm = [float(x) for x in (line[30:38], line[38:45], line[46:54],
line[54:60], line[60:66])]
sigatm_array = numpy.array(sigatm, "f")
structure_builder.set_sigatm(sigatm_array)
local_line_counter += 1
# EOF (does not end in END or CONECT)
self.line_counter = self.line_counter + local_line_counter
return []
def _handle_PDB_exception(self, message, line_counter):
"""
This method catches an exception that occurs in the StructureBuilder
object (if PERMISSIVE), or raises it again, this time adding the
PDB line number to the error message.
"""
message = "%s at line %i." % (message, line_counter)
if self.PERMISSIVE:
# just print a warning - some residues/atoms may be missing
warnings.warn("PDBConstructionException: %s\n"
"Exception ignored.\n"
"Some atoms or residues may be missing in the data structure."
% message, PDBConstructionWarning)
else:
# exceptions are fatal - raise again with new message (including line nr)
raise PDBConstructionException(message)