def _place_between(self, mol: Chem.RWMol, a: int, b: int, aromatic=True):
oribond = mol.GetBondBetweenAtoms(a, b)
if oribond is None:
print('FAIL')
return None # fail
elif aromatic:
bt = Chem.BondType.AROMATIC
else:
bt = oribond.GetBondType()
idx = mol.AddAtom(Chem.Atom(6))
neoatom = mol.GetAtomWithIdx(idx)
atom_a = mol.GetAtomWithIdx(a)
atom_b = mol.GetAtomWithIdx(b)
if aromatic:
neoatom.SetIsAromatic(True)
atom_a.SetIsAromatic(True)
atom_b.SetIsAromatic(True)
# prevent constraints
neoatom.SetBoolProp('_Novel', True)
atom_a.SetBoolProp('_Novel', True)
atom_b.SetBoolProp('_Novel', True)
# fix position
conf = mol.GetConformer()
pos_A = conf.GetAtomPosition(a)
pos_B = conf.GetAtomPosition(b)
x = pos_A.x / 2 + pos_B.x / 2
y = pos_A.y / 2 + pos_B.y / 2
z = pos_A.z / 2 + pos_B.z / 2
conf.SetAtomPosition(idx, Point3D(x, y, z))
# fix bonds
mol.RemoveBond(a, b)
mol.AddBond(a, idx, bt)
mol.AddBond(b, idx, bt)
def apply(self, mol: RWMol) -> RWMol:
atom1 = get_atom_ind(mol, self.atom_map1)
atom2 = get_atom_ind(mol, self.atom_map2)
if self.bond_type is None: # delete bond
bond = mol.GetBondBetweenAtoms(atom1, atom2)
if bond is not None:
mol.RemoveBond(atom1, atom2)
else:
b_type = rdchem.BondType.values[self.bond_type]
b_stereo = rdchem.BondStereo.values[self.bond_stereo]
bond = mol.GetBondBetweenAtoms(atom1, atom2)
if bond is None: # add new bond
bond_ind = mol.AddBond(atom1, atom2, order=b_type) - 1
bond = mol.GetBondWithIdx(bond_ind)
else: # change an existing bond
bond.SetBondType(b_type)
bond.SetStereo(b_stereo)
bond.SetBoolProp('is_edited', True)
if b_type == BondType.AROMATIC:
bond.SetIsAromatic(True)
mol.GetAtomWithIdx(atom1).SetIsAromatic(True)
mol.GetAtomWithIdx(atom2).SetIsAromatic(True)
return mol
def apply(self, mol: RWMol) -> RWMol:
num_atoms = mol.GetNumAtoms()
if self.detach:
for i, a in enumerate(mol.GetAtoms()):
m = a.GetAtomMapNum()
if m == self.atom_map2:
for bond in a.GetBonds():
mol.RemoveBond(bond.GetBeginAtomIdx(),
bond.GetEndAtomIdx())
mol.RemoveAtom(i)
num_atoms -= 1
break
atom_ind = get_atom_ind(mol, self.atom_map1)
b_type = rdchem.BondType.values[self.bond_type]
b_stereo = rdchem.BondStereo.values[self.bond_stereo]
old_atom = mol.GetAtomWithIdx(atom_ind)
if old_atom.HasProp('in_reactant'):
self.new_a.SetBoolProp('in_reactant',
old_atom.GetBoolProp('in_reactant'))
if old_atom.HasProp('mol_id'):
self.new_a.SetIntProp('mol_id', old_atom.GetIntProp('mol_id'))
mol.AddAtom(self.new_a)
new_atom_ind = num_atoms
bond_ind = mol.AddBond(atom_ind, new_atom_ind, order=b_type) - 1
new_bond = mol.GetBondWithIdx(bond_ind)
new_bond.SetStereo(b_stereo)
new_bond.SetBoolProp('is_edited', True)
return mol
def _prevent_bridge_ring(self, mol: Chem.RWMol, examplar: Tuple[int]):
## This is really
# examplar is ring
ringatoms = self._get_ring_info(mol) #GetRingInfo().AtomRings()
ringatoms = [ring for ring in ringatoms if set(ring).intersection(examplar)]
ring_idx = list(range(len(ringatoms)))
shared_count = {}
for ra, rb in itertools.combinations(ring_idx, r=2):
shared_count[(ra, rb)] = len(set(ringatoms[ra]).intersection(set(ringatoms[rb])))
if len(shared_count) == 0:
return mol
ra, rb = list(shared_count.keys())[0]
shared = list(set(ringatoms[ra]).intersection(ringatoms[rb]))
pairs = [(a, b) for a, b in itertools.combinations(shared, r=2) if mol.GetBondBetweenAtoms(a, b) is not None]
c = Counter([i for pair in pairs for i in pair])
ring_A, ring_B = ringatoms[ra], ringatoms[rb]
small, big = sorted([ring_A, ring_B], key=lambda ring: len(ring))
inners = [i for i in c if c[i] > 1]
x = list(set(shared).difference(inners))
if len(x) != 2:
log.critical(f'This is impossible. {ringatoms} share {shared} with {inners} in the inside and {x} on the edge?')
return mol
a, b = x
if len(big) > 6:
log.warning(f'Removing {len(inners)} bridging atoms and replacing with fused ring')
# bond the vertices
bt = Chem.BondType.SINGLE # ???
if mol.GetBondBetweenAtoms(a, b) is None:
mol.AddBond(a, b, bt)
else:
log.warning('This is really odd! Why is there a bond already??')
# remove the middle atoms.
for i in sorted(inners, reverse=True):
mol.RemoveAtom(i)
else:
log.warning(f'Shriking the smaller ring to change from bridged to fused.')
# get the neighbour in the small atom to a vertex.
neighs = [neigh for neigh in mol.GetAtomWithIdx(a).GetNeighbors() if
neigh.GetIdx() not in shared and neigh.GetIdx() in small]
neigh = sorted(neighs, key=lambda atom: atom.GetSymbol() != 'C')[0]
bt = mol.GetBondBetweenAtoms(a, neigh.GetIdx()).GetBondType()
mol.RemoveBond(a, neigh.GetIdx())
new_neigh = [neigh for neigh in mol.GetAtomWithIdx(a).GetNeighbors() if neigh.GetIdx() in shared][0]
mol.AddBond(neigh.GetIdx(), new_neigh.GetIdx(), bt)
neigh.SetBoolProp('_Novel', True)
new_neigh.SetBoolProp('_Novel', True)
mol.GetAtomWithIdx(a).SetBoolProp('_Novel', True)
return mol
def _minimize_rings(mol):
"""Private: Minimize rings in a scaffold.
In this process, all remaining vertices/atoms of degree two are
removed by performing an edge merging operation. The only
exception being when both vertices neighbours are connected
(i.e. we have a triangle), when edge merging would lead to the
loss of a cycle. The result is a minimum cycle topological
representation of the original molecule. This function is used
in the computation of ring topology scaffolds (Oprea).
If a ring contains a non-carbon atom, this atom is maintained.
Neighbouring ring atoms which are of the same type are merged
together into a single atom of the corresponding type.
Parameters
----------
mol : rdkit.Chem.rdchem.Mol
Returns
-------
rdkit.Chem.rdchem.RWMol
Minimum cycle topological graph.
"""
edit = RWMol(mol)
remove_atoms = set()
for atom in edit.GetAtoms():
if atom.GetDegree() == 2:
n1, n2 = atom.GetNeighbors()
n1_idx, n2_idx = n1.GetIdx(), n2.GetIdx()
connected = edit.GetBondBetweenAtoms(n1_idx, n2_idx)
if not connected and (n1.GetAtomicNum() == atom.GetAtomicNum()
or n2.GetAtomicNum() == atom.GetAtomicNum()):
a_idx = atom.GetIdx()
edit.RemoveBond(n1_idx, a_idx)
edit.RemoveBond(n2_idx, a_idx)
edit.AddBond(n1_idx, n2_idx, BondType.SINGLE)
remove_atoms.add(a_idx)
for a_idx in sorted(remove_atoms, reverse=True):
edit.RemoveAtom(a_idx)
return edit
def fragment(self, scaffold):
"""Fragment a scaffold into its next set of Murcko fragments.
Parameters
----------
scaffold : scaffoldgraph.core.Scaffold
Child scaffold to be fragmented.
Returns
-------
list
A list of parent scaffolds representing the next hierarchy.
"""
parents = [] # container for parent scaffolds
rings = scaffold.rings # ring information
for rix, ring in enumerate(rings): # Loop through all rings and remove
edit = RWMol(scaffold.mol) # Editable molecule
# Collect all removable atoms in the molecule
remove_atoms = set()
for index, atom in zip(ring.aix, ring.atoms):
if rings.info.NumAtomRings(index) == 1:
if atom.GetDegree() > 2: # Evoke linker collection
collect_linker_atoms(edit.GetAtomWithIdx(index),
remove_atoms)
else: # Add ring atom to removable set
remove_atoms.add(index)
else: # Atom is shared between multiple rings
correct_atom_props(edit.GetAtomWithIdx(index))
# Collect removable bonds (this needs to be done to prevent the case where when deleting
# a ring two atoms belonging to the same bond are also part of separate other rings.
# This bond must be broken to prevent an incorrect output)
remove_bonds = set()
for bix in {
x
for x in ring.bix if rings.info.NumBondRings(x) == 1
}:
bond = edit.GetBondWithIdx(bix)
b_x, b_y = bond.GetBeginAtomIdx(), bond.GetEndAtomIdx()
if b_x not in remove_atoms and b_y not in remove_atoms:
remove_bonds.add((b_x, b_y))
correct_atom_props(edit.GetAtomWithIdx(b_x))
correct_atom_props(edit.GetAtomWithIdx(b_y))
# Scheme 4 (scaffold tree rule)
if self.use_scheme_4 is not False and len(ring) == 3:
atomic_nums = [a.GetAtomicNum() for a in ring.atoms]
if len([a for a in atomic_nums if a != 1 and a != 6]) == 1:
shared = {
x
for x in ring.bix if rings.info.NumBondRings(x) > 1
}
if len(shared) == 1:
bond = edit.GetBondWithIdx(shared.pop())
bond.SetBondType(BondType.DOUBLE)
# Remove collected atoms and bonds
for bix in remove_bonds:
edit.RemoveBond(*bix)
for aix in sorted(remove_atoms, reverse=True):
edit.RemoveAtom(aix)
# Add new parent scaffolds to parent list
for parent in get_scaffold_frags(edit):
if parent.rings.count == len(rings) - 1:
parent.removed_ring_idx = rix
parents.append(parent)
return parents