CDPL.Chem.HashCodeCalculator Class Reference

Computes a 64-bit hash code that identifies a molecular graph up to a configurable set of atom and bond properties. More...

Inheritance diagram for CDPL.Chem.HashCodeCalculator:

Classes
class	DefAtomHashSeedFunctor
	The default functor for the generation of atom hash seeds. More...
class	DefBondHashSeedFunctor
	The default functor for the generation of bond hash seeds. More...

Public Member Functions
None	__init__ ()
	Constructs the HashCodeCalculator instance.
None	__init__ (MolecularGraph molgraph)
	Constructs the HashCodeCalculator instance and calculates the hash code of the molecular graph molgraph. More...
int	getObjectID ()
	Returns the numeric identifier (ID) of the wrapped C++ class instance. More...
None	setAtomHashSeedFunction (SizeTypeAtomFunctor func)
	Allows to specify a custom function for the generation of initial atom hash codes. More...
None	setBondHashSeedFunction (UInt64BondFunctor func)
	Allows to specify a custom function for the generation of initial bond hash codes. More...
int	calculate (MolecularGraph molgraph)
	Calculates the hash code of the molecular graph molgraph. More...
int	getResult ()
	Returns the result of the last hash code calculation. More...
int	__call__ (MolecularGraph molgraph)

Static Public Attributes
int	DEF_ATOM_PROPERTY_FLAGS = 159
	Specifies the default set of atomic properties considered in the generation of initial atom hash codes by HashCodeCalculator.DefAtomHashSeedFunction.
int	DEF_BOND_PROPERTY_FLAGS = 15
	Specifies the default set of bond properties considered in the generation of initial bond hash codes by HashCodeCalculator.DefBondHashSeedFunction.

Properties
	objectID = property(getObjectID)
	result = property(getResult)

Detailed Description

Computes a 64-bit hash code that identifies a molecular graph up to a configurable set of atom and bond properties.

The algorithm assigns initial seeds to each atom and bond through the user-replaceable functors HashCodeCalculator.AtomHashSeedFunction and HashCodeCalculator.BondHashSeedFunction, iteratively propagates the seeds over the graph topology in the spirit of Morgan-style extended-connectivity hashing, and finally folds the per-atom hash codes into a single std::uint64_t result via an SHA-style mixing step. The default seed functors (DefAtomHashSeedFunctor, DefBondHashSeedFunctor) take into account the property flags combined into DEF_ATOM_PROPERTY_FLAGS and DEF_BOND_PROPERTY_FLAGS, respectively.

See also

[MHASH]

Constructor & Destructor Documentation

__init__()

None CDPL.Chem.HashCodeCalculator.__init__

(

MolecularGraph

molgraph

)

Constructs the HashCodeCalculator instance and calculates the hash code of the molecular graph molgraph.

The calculated hash code can be retrieved by a call to getResult().

Parameters

molgraph

The molecular graph for which the hash code has to be calculated.

Member Function Documentation

getObjectID()

int CDPL.Chem.HashCodeCalculator.getObjectID

(

)

Returns the numeric identifier (ID) of the wrapped C++ class instance.

Different Python HashCodeCalculator instances may reference the same underlying C++ class instance. The commonly used Python expression a is not b thus cannot tell reliably whether the two HashCodeCalculator instances a and b reference different C++ objects. The numeric identifier returned by this method allows to correctly implement such an identity test via the simple expression a.getObjectID() != b.getObjectID().

Returns

The numeric ID of the internally referenced C++ class instance.

setAtomHashSeedFunction()

None CDPL.Chem.HashCodeCalculator.setAtomHashSeedFunction

(

SizeTypeAtomFunctor

func

)

Allows to specify a custom function for the generation of initial atom hash codes.

Parameters

func	A HashCodeCalculator.AtomHashSeedFunction instance that wraps the target function.

Note

By default, atom hash seeds are generated by HashCodeCalculator.DefAtomHashSeedFunctor.

setBondHashSeedFunction()

None CDPL.Chem.HashCodeCalculator.setBondHashSeedFunction

(

UInt64BondFunctor

func

)

Allows to specify a custom function for the generation of initial bond hash codes.

Parameters

func	A HashCodeCalculator.BondHashSeedFunction instance that wraps the target function.

Note

By default, bond hash seeds are generated by HashCodeCalculator.DefBondHashSeedFunctor.

calculate()

int CDPL.Chem.HashCodeCalculator.calculate

(

MolecularGraph

molgraph

)

Calculates the hash code of the molecular graph molgraph.

Parameters

molgraph

The molecular graph for which to calculate the hash code.

Returns

The hash code of the molecular graph molgraph.

getResult()

int CDPL.Chem.HashCodeCalculator.getResult

(

)

Returns the result of the last hash code calculation.

Returns

The result of the last hash code calculation, or zero if a calculation has not yet been performed.

__call__()

int CDPL.Chem.HashCodeCalculator.__call__

(

MolecularGraph

molgraph

)

Parameters

molgraph

Returns