def read_topology_file(self, tfile):
"""
Reads _only_ the atom type definitions from a topology file. This is
unnecessary for versions 36 and later of the CHARMM force field.
Parameters
----------
tfile : str
Name of the CHARMM topology file to read
"""
conv = CharmmParameterSet._convert
if isinstance(tfile, str):
own_handle = True
f = iter(CharmmFile(tfile))
else:
own_handle = False
f = tfile
hpatch = tpatch = None # default Head and Tail patches
residues = dict()
patches = dict()
hpatches = dict()
tpatches = dict()
line = next(f)
try:
while line:
line = line.strip()
if line[:4] == "MASS":
words = line.split()
try:
idx = conv(words[1], int, "atom type")
name = words[2].upper()
mass = conv(words[3], float, "atom mass")
except IndexError:
raise CharmmError("Could not parse MASS section of %s" % tfile)
# The parameter file might or might not have an element name
try:
elem = words[4].upper()
if len(elem) == 2:
elem = elem[0] + elem[1].lower()
atomic_number = AtomicNum[elem]
except (IndexError, KeyError):
# Figure it out from the mass
atomic_number = AtomicNum[element_by_mass(mass)]
atype = AtomType(name=name, number=idx, mass=mass, atomic_number=atomic_number)
self.atom_types_str[atype.name] = atype
self.atom_types_int[atype.number] = atype
self.atom_types_tuple[(atype.name, atype.number)] = atype
elif line[:4] == "DECL":
pass # Not really sure what this means
elif line[:4] == "DEFA":
words = line.split()
if len(words) < 5:
warnings.warn("DEFA line has %d tokens; expected 5" % len(words))
else:
it = iter(words[1:5])
for tok, val in zip(it, it):
if val.upper() == "NONE":
val = None
if tok.upper().startswith("FIRS"):
hpatch = val
elif tok.upper() == "LAST":
tpatch = val
else:
warnings.warn("DEFA patch %s unknown" % val)
elif line[:4].upper() in ("RESI", "PRES"):
restype = line[:4].upper()
# Get the residue definition
words = line.split()
resname = words[1].upper()
# Assign default patches
hpatches[resname] = hpatch
tpatches[resname] = tpatch
try:
charge = float(words[2])
except (IndexError, ValueError):
warnings.warn("No charge for %s" % resname)
if restype == "RESI":
res = ResidueTemplate(resname)
elif restype == "PRES":
res = PatchTemplate(resname)
else:
assert False, "restype != RESI or PRES"
line = next(f)
group = []
ictable = []
while line:
line = line.lstrip()
if line[:5].upper() == "GROUP":
if group:
res.groups.append(group)
group = []
elif line[:4].upper() == "ATOM":
words = line.split()
name = words[1].upper()
type = words[2].upper()
charge = float(words[3])
atom = Atom(name=name, type=type, charge=charge)
group.append(atom)
res.add_atom(atom)
elif line.strip() and line.split()[0].upper() in ("BOND", "DOUBLE"):
it = iter([w.upper() for w in line.split()[1:]])
for a1, a2 in zip(it, it):
if a1.startswith("-"):
res.head = res[a2]
continue
if a2.startswith("-"):
res.head = res[a1]
continue
if a1.startswith("+"):
res.tail = res[a2]
continue
if a2.startswith("+"):
res.tail = res[a1]
continue
# Apparently PRES objects do not need to put +
# or - in front of atoms that belong to adjacent
# residues
if restype == "PRES" and (a1 not in res or a2 not in res):
continue
res.add_bond(a1, a2)
elif line[:4].upper() == "CMAP":
pass
elif line[:5].upper() == "DONOR":
pass
elif line[:6].upper() == "ACCEPT":
pass
elif line[:2].upper() == "IC":
words = line.split()[1:]
ictable.append(([w.upper() for w in words[:4]], [float(w) for w in words[4:]]))
elif line[:3].upper() == "END":
break
elif line[:5].upper() == "PATCH":
it = iter(line.split()[1:])
for tok, val in zip(it, it):
if val.upper() == "NONE":
val = None
if tok.upper().startswith("FIRS"):
hpatches[resname] = val
elif tok.upper().startswith("LAST"):
tpatches[resname] = val
elif line[:5].upper() == "DELETE":
pass
elif line[:4].upper() == "IMPR":
it = iter([w.upper() for w in line.split()[1:]])
for a1, a2, a3, a4 in zip(it, it, it, it):
if a2[0] == "-" or a3[0] == "-" or a4 == "-":
res.head = res[a1]
elif line[:4].upper() in ("RESI", "PRES", "MASS"):
# Back up a line and bail
break
line = next(f)
if group:
res.groups.append(group)
_fit_IC_table(res, ictable)
if restype == "RESI":
residues[resname] = res
elif restype == "PRES":
patches[resname] = res
else:
assert False, "restype != RESI or PRES"
# We parsed a line we need to look at. So don't update the
# iterator
continue
# Get the next line and cycle through
line = next(f)
except StopIteration:
pass
# Go through the patches and add the appropriate one
for resname, res in iteritems(residues):
if hpatches[resname] is not None:
try:
res.first_patch = patches[hpatches[resname]]
except KeyError:
warnings.warn("Patch %s not found" % hpatches[resname])
if tpatches[resname] is not None:
try:
res.last_patch = patches[tpatches[resname]]
except KeyError:
warnings.warn("Patch %s not found" % tpatches[resname])
# Now update the residues and patches with the ones we parsed here
self.residues.update(residues)
self.patches.update(patches)
if own_handle:
f.close()
def parse(filename, structure=False):
""" Parses a mol2 file (or mol3) file
Parameters
----------
filename : str or file-like
Name of the file to parse or file-like object to parse from
structure : bool, optional
If True, the return value is a :class:`Structure` instance. If
False, it is either a :class:`ResidueTemplate` or
:class:`ResidueTemplateContainter` instance, depending on whether
there is one or more than one residue defined in it. Default is
False
Returns
-------
molecule : :class:`Structure`, :class:`ResidueTemplate`, or
:class:`ResidueTemplateContainer`
The molecule defined by this mol2 file
Raises
------
Mol2Error
If the file format is not recognized or non-numeric values are
present where integers or floating point numbers are expected. Also
raises Mol2Error if you try to parse a mol2 file that has multiple
@<MOLECULE> entries with ``structure=True``.
"""
if isinstance(filename, string_types):
f = genopen(filename, 'r')
own_handle = True
else:
f = filename
own_handle = False
rescont = ResidueTemplateContainer()
struct = Structure()
restemp = ResidueTemplate()
mol_info = []
multires_structure = False
try:
section = None
last_residue = None
headtail = 'head'
molecule_number = 0
for line in f:
if line.startswith('#'): continue
if not line.strip() and section is None: continue
if line.startswith('@<TRIPOS>'):
section = line[9:].strip()
if section == 'MOLECULE' and (restemp.atoms or rescont):
if structure:
raise Mol2Error('Cannot convert MOL2 with multiple '
'@<MOLECULE>s to a Structure')
# Set the residue name from the MOL2 title if the
# molecule had only 1 residue and it was given a name in
# the title
if not multires_structure and mol_info[0]:
restemp.name = mol_info[0]
multires_structure = False
rescont.append(restemp)
restemp = ResidueTemplate()
struct = Structure()
last_residue = None
molecule_number += 1
mol_info = []
continue
if section is None:
raise Mol2Error('Bad mol2 file format')
if section == 'MOLECULE':
# Section formatted as follows:
# mol_name
# num_atoms [num_bonds [num_substr [num_feat [num_sets]]]]
# mol_type
# charge_type
# [status_bits]
# [mol_comment]
# TODO: Do something with the name.
if len(mol_info) == 0:
mol_info.append(line.strip())
elif len(mol_info) == 1:
mol_info.append([int(x) for x in line.split()])
elif len(mol_info) == 2:
mol_info.append(line.strip())
elif len(mol_info) == 3:
mol_info.append(line.strip())
# Ignore the rest
continue
if section == 'ATOM':
# Section formatted as follows:
# atom_id -- serial number of atom
# atom_name -- name of the atom
# x -- X-coordinate of the atom
# y -- Y-coordinate of the atom
# z -- Z-coordinate of the atom
# atom_type -- type of the atom
# subst_id -- Residue serial number
# subst_name -- Residue name
# charge -- partial atomic charge
# status_bit -- ignored
words = line.split()
id = int(words[0])
name = words[1]
x = float(words[2])
y = float(words[3])
z = float(words[4])
typ = words[5]
try:
resid = int(words[6])
except IndexError:
resid = 0
try:
resname = words[7]
except IndexError:
resname = 'UNK'
if 'NO_CHARGES' not in mol_info:
try:
charge = float(words[8])
except IndexError:
charge = 0
else:
charge = 0
if last_residue is None:
last_residue = (resid, resname)
restemp.name = resname
atom = Atom(name=name, type=typ, number=id, charge=charge)
atom.xx, atom.xy, atom.xz = x, y, z
struct.add_atom(atom, resname, resid)
if last_residue != (resid, resname):
rescont.append(restemp)
restemp = ResidueTemplate()
restemp.name = resname
last_residue = (resid, resname)
multires_structure = True
restemp.add_atom(copy.copy(atom))
continue
if section == 'BOND':
# Section formatted as follows:
# bond_id -- serial number of bond (ignored)
# origin_atom_id -- serial number of first atom in bond
# target_atom_id -- serial number of other atom in bond
# bond_type -- string describing bond type (ignored)
# status_bits -- ignored
words = line.split()
int(words[0]) # Bond serial number... redundant and ignored
a1 = int(words[1])
a2 = int(words[2])
atom1 = struct.atoms.find_original_index(a1)
atom2 = struct.atoms.find_original_index(a2)
struct.bonds.append(Bond(atom1, atom2))
# Now add it to our residue container
# See if it's a head/tail connection
if atom1.residue is not atom2.residue:
if atom1.residue.idx == len(rescont):
res1 = restemp
elif atom1.residue.idx < len(rescont):
res1 = rescont[atom1.residue.idx]
else:
raise Mol2Error('Bad bonding pattern detected')
if atom2.residue.idx == len(rescont):
res2 = restemp
elif atom1.residue.idx < len(rescont):
res2 = rescont[atom2.residue.idx]
else:
raise Mol2Error('Bad bonding pattern detected')
assert res1 is not res2, 'BAD identical residues'
idx1 = atom1.idx - atom1.residue[0].idx
idx2 = atom2.idx - atom2.residue[0].idx
if atom1.residue.idx < atom2.residue.idx:
res1.tail = res1[idx1]
res2.head = res2[idx2]
else:
res1.head = res1[idx1]
res2.tail = res2[idx2]
elif not multires_structure:
restemp.add_bond(a1-1, a2-1)
else:
# Same residue, add the bond
offset = atom1.residue[0].idx
if atom1.residue.idx == len(rescont):
res = restemp
else:
res = rescont[atom1.residue.idx]
res.add_bond(atom1.idx-offset, atom2.idx-offset)
continue
if section == 'CRYSIN':
# Section formatted as follows:
# a -- length of first unit cell vector
# b -- length of second unit cell vector
# c -- length of third unit cell vector
# alpha -- angle b/w b and c
# beta -- angle b/w a and c
# gamma -- angle b/w a and b
# space group -- number of space group (ignored)
# space group setting -- ignored
words = line.split()
box = [float(x) for x in words[:6]]
if len(box) != 6:
raise ValueError('%d box dimensions found; needed 6' %
len(box))
struct.box = copy.copy(box)
rescont.box = copy.copy(box)
continue
if section == 'SUBSTRUCTURE':
# Section formatted as follows:
# subst_id -- residue number
# subst_name -- residue name
# root_atom -- first atom of residue
# subst_type -- ignored (usually 'RESIDUE')
# dict_type -- type of substructure (ignored)
# chain -- chain ID of residue
# sub_type -- type of the chain
# inter_bonds -- # of inter-substructure bonds
# status -- ignored
# comment -- ignored
words = line.split()
if not words: continue
id = int(words[0])
resname = words[1]
try:
chain = words[5]
except IndexError:
chain = ''
# Set the chain ID
for res in struct.residues:
if res.number == id and res.name == resname:
res.chain = chain
continue
# MOL3 sections
if section == 'HEADTAIL':
atname, residx = line.split()
residx = int(residx)
if residx in (0, 1) or residx - 1 == len(rescont):
res = restemp
elif residx - 1 < len(rescont):
res = rescont[residx-1]
else:
raise Mol2Error('Residue out of range in head/tail')
for atom in res:
if atom.name == atname:
if headtail == 'head':
res.head = atom
headtail = 'tail'
else:
res.tail = atom
headtail = 'head'
break
else:
if headtail == 'head':
headtail = 'tail'
else:
headtail = 'head'
continue
if section == 'RESIDUECONNECT':
words = line.split()
residx = int(words[0])
if residx - 1 == len(rescont):
res = restemp
elif residx - 1 < len(rescont):
res = rescont[residx-1]
else:
raise Mol2Error('Residue out of range in '
'residueconnect')
for a in words[3:]:
if a == '0': continue
for atom in res:
if atom.name == a:
atom.connections.append(atom)
break
else:
raise Mol2Error('Residue connection atom %s not '
'found in residue %d' % (a, residx))
if structure:
return struct
elif len(rescont) > 0:
if not multires_structure and mol_info[0]:
restemp.name = mol_info[0]
rescont.append(restemp)
return rescont
else:
return restemp
except ValueError as e:
raise Mol2Error('String conversion trouble: %s' % e)
finally:
if own_handle: f.close()