class Walker(metaclass=abc.ABCMeta):
"""Base class for the walking strategies.
Attributes:
depth: The depth per entity.
max_walks: The maximum number of walks per entity.
sampler: The sampling strategy.
Defaults to UniformSampler().
n_jobs: The number of processes to use for multiprocessing. Use -1 to
allocate as many processes as there are CPU cores available in the
machine.
Defaults to 1.
is_support_remote: If true, indicate that the walking strategy can be
used to retrieve walks via a SPARQL endpoint server.
Defaults to False.
"""
# Global KG used later on for the worker process.
kg = None
def __init__(
self,
depth: int,
max_walks: Optional[int] = None,
sampler: Optional[Sampler] = None,
n_jobs: int = 1,
is_support_remote: bool = True,
):
self.depth = depth
self.is_support_remote = is_support_remote
if n_jobs == -1:
self.n_jobs = multiprocessing.cpu_count()
else:
self.n_jobs = n_jobs
self.max_walks = max_walks
if sampler is not None:
self.sampler = sampler
else:
self.sampler = UniformSampler()
def extract(
self, kg: KG, instances: List[rdflib.URIRef], verbose=False
) -> Set[Tuple[Any, ...]]:
"""Fits the provided sampling strategy and then calls the
private _extract method that is implemented for each of the
walking strategies.
Args:
kg: The Knowledge Graph.
The graph from which the neighborhoods are extracted for the
provided instances.
instances: The instances to be extracted from the Knowledge Graph.
verbose: If true, display a progress bar for the extraction of the
walks.
Returns:
The 2D matrix with its number of rows equal to the number of
provided instances; number of column equal to the embedding size.
"""
if kg.is_remote and not self.is_support_remote:
raise RemoteNotSupported(
"Invalid walking strategy. Please, choose a walking strategy "
+ "that can retrieve walks via a SPARQL endpoint server."
)
self.sampler.fit(kg)
canonical_walks = set()
# To avoid circular imports
if "CommunityWalker" in str(self):
self._community_detection(kg) # type: ignore
if kg.is_remote:
asyncio.run(kg._fill_entity_hops(instances)) # type: ignore
with multiprocessing.Pool(
self.n_jobs, self._init_worker, [kg]
) as pool:
res = list(
tqdm(
pool.imap_unordered(self._proc, instances),
total=len(instances),
disable=not verbose,
)
)
res = {k: v for elm in res for k, v in elm.items()} # type: ignore
for instance in instances:
canonical_walks.update(res[instance])
return canonical_walks
@abc.abstractmethod
def _extract(
self, kg: KG, instance: rdflib.URIRef
) -> Dict[Any, Tuple[Tuple[str, ...], ...]]:
"""Extracts walks rooted at the provided instances which are then each
transformed into a numerical representation.
Args:
kg: The Knowledge Graph.
The graph from which the neighborhoods are extracted for the
provided instances.
instance: The instance to be extracted from the Knowledge Graph.
Returns:
The 2D matrix with its number of rows equal to the number of
provided instances; number of column equal to the embedding size.
"""
raise NotImplementedError("This must be implemented!")
def _init_worker(self, init_kg):
"""Initializes each worker process.
Args:
init_kg: The Knowledge Graph to provide to each worker process.
"""
global kg
kg = init_kg
def info(self):
"""Gets informations related to a Walker.
Returns:
A friendly display of the Walker.
"""
return (
f"{type(self).__name__}(depth={self.depth},"
+ f"max_walks={self.max_walks},"
+ f"sampler={type(self.sampler).__name__},"
+ f"n_jobs={self.n_jobs},"
+ f"is_support_remote={self.is_support_remote})"
)
def print_walks(
self,
kg: KG,
instances: List[rdflib.URIRef],
filename: str,
) -> None:
"""Prints the walks of a Knowledge Graph.
Args:
kg: The Knowledge Graph.
The graph from which the neighborhoods are extracted for the
provided instances.
instances: The instances to be extracted from the Knowledge Graph.
filename: The filename that contains the rdflib.Graph
"""
walks = self.extract(kg, instances)
walk_strs = []
for _, walk in enumerate(walks):
s = ""
for i in range(len(walk)):
s += f"{walk[i]} "
if i < len(walk) - 1:
s += "--> "
walk_strs.append(s)
with open(filename, "w+") as f:
for s in walk_strs:
f.write(s)
f.write("\n\n")
def _proc(
self, instance: rdflib.URIRef
) -> Dict[Any, Tuple[Tuple[str, ...], ...]]:
"""Executed by each process.
Args:
instance: The instance to be extracted from the Knowledge Graph.
Returns:
The extraction of walk by the process.
"""
global kg
return self._extract(kg, instance) # type:ignore
class Walker(metaclass=abc.ABCMeta):
"""Base class for the walking strategies.
Attributes:
depth: The depth per entity.
walks_per_graph: The maximum number of walks per entity.
sampler: The sampling strategy.
Default to UniformSampler().
"""
def __init__(
self,
depth: int,
walks_per_graph: float,
sampler: Sampler = None,
):
self.depth = depth
self.walks_per_graph = walks_per_graph
if sampler is not None:
self.sampler = sampler
else:
self.sampler = UniformSampler()
def extract(
self, kg: KG, instances: List[rdflib.URIRef]
) -> Set[Tuple[Any, ...]]:
"""Fits the provided sampling strategy and then calls the
private _extract method that is implemented for each of the
walking strategies.
Args:
graph: The knowledge graph.
The graph from which the neighborhoods are extracted for the
provided instances.
instances: The instances to extract the knowledge graph.
Returns:
The 2D matrix with its number of rows equal to the number of
provided instances; number of column equal to the embedding size.
"""
self.sampler.fit(kg)
return self._extract(kg, instances)
@abc.abstractmethod
def _extract(
self, kg: KG, instances: List[rdflib.URIRef]
) -> Set[Tuple[Any, ...]]:
"""Extracts walks rooted at the provided instances which are then each
transformed into a numerical representation.
Args:
graph: The knowledge graph.
The graph from which the neighborhoods are extracted for the
provided instances.
instances: The instances to extract the knowledge graph.
Returns:
The 2D matrix with its number of rows equal to the number of
provided instances; number of column equal to the embedding size.
"""
raise NotImplementedError("This must be implemented!")
def print_walks(
self,
kg: KG,
instances: List[rdflib.URIRef],
file_name: str,
) -> None:
"""Prints the walks of a knowledge graph.
Args:
kg: The knowledge graph.
The graph from which the neighborhoods are extracted for the
provided instances.
instances: The instances to extract the knowledge graph.
file_name: The filename that contains the rdflib.Graph
"""
walks = self.extract(kg, instances)
walk_strs = []
for _, walk in enumerate(walks):
s = ""
for i in range(len(walk)):
s += f"{walk[i]} "
if i < len(walk) - 1:
s += "--> "
walk_strs.append(s)
with open(file_name, "w+") as f:
for s in walk_strs:
f.write(s)
f.write("\n\n")
