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# Copyright (C) 2002, Thomas Hamelryck (thamelry@binf.ku.dk)
# This code is part of the Biopython distribution and governed by its
# license. Please see the LICENSE file that should have been included
# as part of this package.
"""mmCIF parser"""
from __future__ import print_function
from string import ascii_letters
import numpy
from Bio._py3k import range
from Bio.PDB.MMCIF2Dict import MMCIF2Dict
from Bio.PDB.StructureBuilder import StructureBuilder
from Bio.PDB.PDBExceptions import PDBConstructionException
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
if __name__=="__main__":
import sys
if len(sys.argv) != 2:
print("Usage: python MMCIFparser.py filename")
raise SystemExit
filename=sys.argv[1]
p=MMCIFParser()
structure=p.get_structure("test", filename)
for model in structure.get_list():
print(model)
for chain in model.get_list():
print(chain)
print("Found %d residues." % len(chain.get_list()))
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