from __future__ import annotations
import typing
from stk._internal.atom import Atom
_T = typing.TypeVar("_T", bound="FunctionalGroup")
[docs]
class FunctionalGroup:
"""
An abstract base class for functional groups.
It is used to give access to atoms of :class:`.BuildingBlock`
molecules which are modified during
:class:`.ConstructedMolecule` construction, as well as specify
which atoms of the building block should be used for positioning.
*Should I use* :meth:`.with_ids` *or* :meth:`.with_atoms` *?*
That depends on your use case, however, it is generally better to
default to :meth:`.with_ids` unless you need to actually change
the atoms held by the functional group. This is because
:meth:`.with_ids` preserves the most-derived type of the functional
group, while :meth:`.with_atoms` does not. To give an example
.. testcode:: with-atoms-vs-with-ids
import stk
bromo = stk.Bromo(
bromine=stk.Br(0),
atom=stk.C(1),
bonders=(stk.C(1), ),
deleters=(stk.Br(0), ),
)
bromo2 = bromo.with_ids({
0: 10,
1: 100,
})
# bromo2 is still a Bromo functional group.
assert isinstance(bromo2, stk.Bromo)
not_bromo = bromo.with_atoms({
0: stk.Br(10),
1: stk.C(100),
})
# not_bromo is not a Bromo functional gorup.
assert not isinstance(not_bromo, stk.Bromo)
# However, it is still an instance of FunctionalGroup,
assert isinstance(not_bromo, stk.FunctionalGroup)
# and of GenericFunctionalGroup
assert isinstance(not_bromo, stk.GenericFunctionalGroup)
The reason that :meth:`.with_atoms` does not produce a
:class:`.Bromo` instance is to avoid the following pitfall
.. code-block:: python
pitfall = bromo.with_atoms({
0: stk.F(10),
1: stk.C(100),
})
# If with_atoms() returned a Bromo instance then you could
# call get_bromine() on it, but it would hold a F atom!
this_is_a_fluorine = pitfall.get_bromine()
*Why would I want to implement a new subclass?*
The most common reason you would want to implement a new
:class:`.FunctionalGroup` subclass, is because you want to
customize the construction of a :class:`.ConstructedMolecule`.
Specifically, you want to modify a specific set of atoms in a
:class:`.BuildingBlock` when doing construction, and you want
to modify them in a specific way. You will usually accompany the
creation of the new :class:`.FunctionalGroup` subclass with the
creation of a new :class:`.Reaction` subclass, which will perform
the custom modification on the atoms held by your new
:class:`.FunctionalGroup`
subclass. Finally, a new :class:`.ReactionFactory` will also be
created, so that your :class:`.Reaction` subclass instances
actually get made during construction. Finally, you will pass an
instance of your :class:`.ReactionFactory` subclass to the
chosen :class:`.TopologyGraph` you want to make, for example
:class:`~.polymer.linear.Linear`, and your custom
modification will take place.
See Also:
:mod:`.functional_group_factory`
Used for automated creation of :class:`.FunctionalGroup`
instances.
Notes:
You might notice that some of the methods of this abstract base
class are implemented. This is purely for convenience when
implementing subclasses. The implemented public methods are
simply default implementations, which can be safely ignored
or overridden, when implementing subclasses. Any private
methods are implementation details of these default
implementations.
Examples:
*Subclass Implementation*
The source code of the subclasses, listed in
:mod:`.functional_group`, can serve as good examples.
*Changing the Atoms of a Functional Group*
You want to substitute the atoms in the functional group for
other atoms. You can do this by using :meth:`.with_atoms` to
create a clone of the functional group, which holds the
replacement atoms
.. testcode:: changing-the-atoms-of-a-functional-group
import stk
c, n, h1, h2 = stk.C(0), stk.N(1), stk.H(2), stk.H(3)
amine = stk.PrimaryAmino(
nitrogen=n,
hydrogen1=h1,
hydrogen2=h2,
atom=c,
bonders=(n, ),
deleters=(h1, h2),
)
n20 = stk.N(20)
h100 = stk.H(100)
# amine_clone is a clone of amine, except that instead of
# holding n, amine_clone holds n20, and instead of holding
# h1 amine_clone holds h100. amine_clone continues to hold
# h2.
amine_clone = amine.with_atoms({
n.get_id(): n20,
h1.get_id(): h100,
})
.. testcode:: changing-the-atoms-of-a-functional-group
:hide:
_atoms = set(amine.get_atom_ids())
assert n.get_id() in _atoms
assert n20.get_id() not in _atoms
assert h1.get_id() in _atoms
assert h100.get_id() not in _atoms
_clone_atoms = set(amine_clone.get_atom_ids())
assert n.get_id() not in _clone_atoms
assert n20.get_id() in _clone_atoms
assert h1.get_id() not in _clone_atoms
assert h100.get_id() in _clone_atoms
_bonders = set(amine.get_bonder_ids())
assert n.get_id() in _bonders
assert n20.get_id() not in _bonders
_clone_bonders = set(amine_clone.get_bonder_ids())
assert n.get_id() not in _clone_bonders
assert n20.get_id() in _clone_bonders
_deleters = set(amine.get_deleter_ids())
assert h1.get_id() in _deleters
assert h2.get_id() in _deleters
assert h100.get_id() not in _deleters
_clone_deleters = set(amine_clone.get_deleter_ids())
assert h1.get_id() not in _clone_deleters
assert h2.get_id() in _clone_deleters
assert h100.get_id() in _clone_deleters
"""
def __init__(
self,
atoms: tuple[Atom, ...],
placers: tuple[Atom, ...],
core_atoms: tuple[Atom, ...],
) -> None:
"""
Initialize a :class:`.FunctionalGroup`.
Parameters:
atoms:
The atoms in the functional group.
placers:
The atoms used to calculate the position of the
functional group.
core_atoms:
The atoms of the functional group which also form the
core of the :class:`.BuildingBlock`. See
:meth:`.BuildingBlock.get_core_atom_ids`.
"""
self._atoms = atoms
self._placers = placers
self._core_atoms = core_atoms
[docs]
def get_atoms(self) -> typing.Iterator[Atom]:
"""
Yield all the atoms in the functional group.
Yields:
An atom in the functional group.
"""
yield from self._atoms
[docs]
def get_atom_ids(self) -> typing.Iterator[int]:
"""
Yield the ids of all atoms in the functional group.
Yields:
The id of an :class:`.Atom`.
"""
yield from (a.get_id() for a in self._atoms)
[docs]
def get_placer_ids(self) -> typing.Iterator[int]:
"""
Yield the ids of *placer* atoms.
*Placer* atoms are those, which should be used to calculate
the position of the functional group.
Yields:
The id of an :class:`.Atom`.
"""
yield from (a.get_id() for a in self._placers)
[docs]
def get_core_atom_ids(self) -> typing.Iterator[int]:
"""
Yield the ids of core atoms held by the functional group.
Yields:
The id of an :class:`.Atom`.
See Also:
:meth:`.BuildingBlock.get_core_atom_ids`
"""
yield from (a.get_id() for a in self._core_atoms)
[docs]
def with_atoms(self, atom_map: dict[int, Atom]) -> FunctionalGroup:
"""
Return a clone holding different atoms.
Parameters:
atom_map:
Maps the id of an atom in the functional group to the
new atom the clone should hold. If the id of an atom in
the functional group is not found in `atom_map`, the
atom will not be replaced in the clone.
Returns:
The clone.
"""
# The clone needs to be downcasted.
return FunctionalGroup(
atoms=tuple(atom_map.get(a.get_id(), a) for a in self._atoms),
placers=tuple(atom_map.get(a.get_id(), a) for a in self._placers),
core_atoms=tuple(
atom_map.get(a.get_id(), a) for a in self._core_atoms
),
)
def _with_ids(self, id_map: dict[int, int]) -> FunctionalGroup:
self._atoms = tuple(
atom.with_id(
id=id_map.get(
atom.get_id(),
atom.get_id(),
),
)
for atom in self._atoms
)
self._placers = tuple(
atom.with_id(
id=id_map.get(
atom.get_id(),
atom.get_id(),
),
)
for atom in self._placers
)
self._core_atoms = tuple(
atom.with_id(
id=id_map.get(
atom.get_id(),
atom.get_id(),
),
)
for atom in self._core_atoms
)
return self
[docs]
def with_ids(
self,
id_map: dict[int, int],
) -> FunctionalGroup:
"""
Return a clone holding different atom ids.
Parameters:
id_map:
Maps the id of an atom in the functional group to the
new id the clone should hold. If the id of an atom in
the functional group is not found in `id_map`, the
atom will not be replaced in the clone.
Returns:
The clone.
"""
return self.clone()._with_ids(id_map)
def _clone(self: _T) -> _T:
"""
Return a clone.
Notes:
This method exists so that subclasses can use it and have
correct type information, because the type variable
``_T`` is used. However, I do not want the docs to show
``_T`` I want them to show a proper class, such as
:class:`.Oxygen`. So this method exists for re-use and
type checking, while the public methods exist to provide
a readable type for the docs.
Returns:
A clone.
"""
clone = self.__class__.__new__(self.__class__)
FunctionalGroup.__init__(
self=clone,
atoms=self._atoms,
placers=self._placers,
core_atoms=self._core_atoms,
)
return clone
[docs]
def clone(self) -> FunctionalGroup:
"""
Return a clone.
Returns:
A clone.
"""
return self._clone()
def __str__(self) -> str:
return repr(self)
def __repr__(self) -> str:
return (
f"{self.__class__.__name__}("
f"atoms={self._atoms}, "
f"placers={self._placers}, "
f"core_atoms={self._core_atoms}"
")"
)