def isomorphism(gra1, gra2, backbone_only=False, stereo=True, dummy=True):
""" Obtain an isomorphism between two graphs
This should eventually replace the other isomorphism functions.
:param backbone_only: Compare backbone atoms only?
:type backbone_only: bool
:param stereo: Consider stereo?
:type stereo: bool
:param dummy: Consider dummy atoms?
:type dummy: bool
:returns: The isomorphism mapping `gra1` onto `gra2`
:rtype: dict
"""
if backbone_only:
gra1 = implicit(gra1)
gra2 = implicit(gra2)
if not stereo:
gra1 = without_stereo_parities(gra1)
gra2 = without_stereo_parities(gra2)
if not dummy:
gra1 = without_dummy_atoms(gra1)
gra2 = without_dummy_atoms(gra2)
return _isomorphism(gra1, gra2)
def rotational_symmetry_number(gra, key1, key2, lin_keys=None):
""" get the rotational symmetry number along a given rotational axis
:param gra: the graph
:param key1: the first atom key
:param key2: the second atom key
"""
ngb_keys_dct = atoms_neighbor_atom_keys(without_dummy_atoms(gra))
imp_hyd_vlc_dct = atom_implicit_hydrogen_valences(implicit(gra))
axis_keys = {key1, key2}
# If the keys are part of a linear chain, use the ends of that for the
# symmetry number calculation
lin_keys_lst = linear_segments_atom_keys(gra, lin_keys=lin_keys)
for keys in lin_keys_lst:
if key1 in keys or key2 in keys:
if len(keys) == 1:
key1, key2 = sorted(ngb_keys_dct[keys[0]])
else:
key1, = ngb_keys_dct[keys[0]] - {keys[1]}
key2, = ngb_keys_dct[keys[-1]] - {keys[-2]}
axis_keys |= set(keys)
break
sym_num = 1
for key in (key1, key2):
if key in imp_hyd_vlc_dct:
ngb_keys = ngb_keys_dct[key] - axis_keys
if len(ngb_keys) == imp_hyd_vlc_dct[key] == 3:
sym_num = 3
break
return sym_num
def bond_symmetry_numbers(gra, frm_bnd_key=None, brk_bnd_key=None):
""" symmetry numbers, by bond
the (approximate) symmetry number of the torsional potential for this bond,
based on the hydrogen counts for each atom
It is reduced to 1 if one of the H atoms in the torsional bond is a
neighbor to the special bonding atom (the atom that is being transferred)
"""
imp_gra = implicit(gra)
atm_imp_hyd_vlc_dct = atom_implicit_hydrogen_valences(imp_gra)
bnd_keys = bond_keys(imp_gra)
tfr_atm = None
if frm_bnd_key and brk_bnd_key:
for atm_f in list(frm_bnd_key):
for atm_b in list(brk_bnd_key):
if atm_f == atm_b:
tfr_atm = atm_f
if tfr_atm:
neighbor_dct = atoms_neighbor_atom_keys(gra)
nei_tfr = neighbor_dct[tfr_atm]
atms = gra[0]
all_hyds = []
for atm in atms:
if atms[atm][0] == 'H':
all_hyds.append(atm)
else:
nei_tfr = {}
bnd_symb_num_dct = {}
bnd_symb_nums = []
for bnd_key in bnd_keys:
bnd_sym = 1
vlc = max(map(atm_imp_hyd_vlc_dct.__getitem__, bnd_key))
if vlc == 3:
bnd_sym = 3
if tfr_atm:
for atm in nei_tfr:
nei_s = neighbor_dct[atm]
h_nei = 0
for nei in nei_s:
if nei in all_hyds:
h_nei += 1
if h_nei == 3:
bnd_sym = 1
bnd_symb_nums.append(bnd_sym)
bnd_symb_num_dct = dict(zip(bnd_keys, bnd_symb_nums))
# fill in the rest of the bonds for completeness
bnd_symb_num_dct = dict_.by_key(bnd_symb_num_dct,
bond_keys(gra),
fill_val=1)
return bnd_symb_num_dct
def backbone_isomorphism(gra1, gra2, igraph=False):
""" graph backbone isomorphism
for implicit graphs, this is the relabeling of `gra1` to produce `gra2`
for other graphs, it gives the correspondences between backbone atoms
"""
gra1 = implicit(gra1)
gra2 = implicit(gra2)
if igraph:
igr1 = _igraph.from_graph(gra1)
igr2 = _igraph.from_graph(gra2)
iso_dcts = _igraph.isomorphisms(igr1, igr2)
iso_dct = iso_dcts[0] if iso_dcts else None
else:
nxg1 = _networkx.from_graph(gra1)
nxg2 = _networkx.from_graph(gra2)
iso_dct = _networkx.isomorphism(nxg1, nxg2)
return iso_dct
def is_branched(gra):
""" determine is the molecule has a branched chain
"""
_is_branched = False
gra = implicit(gra)
chain_length = len(longest_chain(gra))
natoms = atom_count(gra, with_implicit=False)
if natoms != chain_length:
_is_branched = True
return _is_branched
def terminal_heavy_atom_keys(gra):
""" terminal heavy atoms, sorted by atom type and hydrogen count
"""
gra = implicit(gra)
atm_imp_hyd_vlc_dct = atom_implicit_hydrogen_valences(gra)
atm_keys = [
key for key, ngb_keys in atoms_neighbor_atom_keys(gra).items()
if len(ngb_keys) == 1
]
atm_keys = sorted(atm_keys,
key=atm_imp_hyd_vlc_dct.__getitem__,
reverse=True)
atm_symbs = dict_.values_by_key(atom_symbols(gra), atm_keys)
srt = automol.formula.argsort_symbols(atm_symbs, symbs_first=('C', ))
atm_keys = tuple(map(atm_keys.__getitem__, srt))
return atm_keys
def linear_atom_keys(rgr, dummy=True):
""" atoms forming linear bonds, based on their hybridization
:param rgr: the graph
:param dummy: whether or not to consider atoms connected to dummy atoms as
linear, if different from what would be predicted based on their
hybridization
:returns: the linear atom keys
:rtype: tuple[int]
"""
rgr = without_fractional_bonds(rgr)
atm_hyb_dct = resonance_dominant_atom_hybridizations(implicit(rgr))
lin_atm_keys = set(dict_.keys_by_value(atm_hyb_dct, lambda x: x == 1))
if dummy:
dum_ngb_key_dct = dummy_atoms_neighbor_atom_key(rgr)
lin_atm_keys |= set(dum_ngb_key_dct.values())
lin_atm_keys = tuple(sorted(lin_atm_keys))
return lin_atm_keys
def _inchi_connected_graph(ich, stereo=True):
""" Generate a molecular graph from an InChI string where
all all atoms are connected by at least one bond.
:param ich: InChI string
d :type ich: str
:param remove_stereo: parameter to include stereochemistry information
:type remove_stereo: bool
:rtype: automol molecular graph
"""
gra = object_from_hardcoded_inchi_by_key('graph', ich)
if gra is None:
ich = standard_form(ich)
if not stereo or not has_stereo(ich):
rdm = _rdkit.from_inchi(ich)
gra = _rdkit.to_connectivity_graph(rdm)
else:
geo = geometry(ich)
gra = graph(geo, stereo=stereo)
gra = implicit(gra)
return gra
