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import torch_geometric
from torch_geometric.data import Data
from torch_geometric.data.datapipes import functional_transform
from torch_geometric.transforms import BaseTransform
from torch_geometric.utils import to_undirected
@functional_transform('knn_graph')
class KNNGraph(BaseTransform):
r"""Creates a k-NN graph based on node positions :obj:`data.pos`
(functional name: :obj:`knn_graph`).
Args:
k (int, optional): The number of neighbors. (default: :obj:`6`)
loop (bool, optional): If :obj:`True`, the graph will contain
self-loops. (default: :obj:`False`)
force_undirected (bool, optional): If set to :obj:`True`, new edges
will be undirected. (default: :obj:`False`)
flow (str, optional): The flow direction when used in combination with
message passing (:obj:`"source_to_target"` or
:obj:`"target_to_source"`).
If set to :obj:`"source_to_target"`, every target node will have
exactly :math:`k` source nodes pointing to it.
(default: :obj:`"source_to_target"`)
cosine (bool, optional): If :obj:`True`, will use the cosine
distance instead of euclidean distance to find nearest neighbors.
(default: :obj:`False`)
num_workers (int): Number of workers to use for computation. Has no
effect in case :obj:`batch` is not :obj:`None`, or the input lies
on the GPU. (default: :obj:`1`)
"""
def __init__(
self,
k: int = 6,
loop: bool = False,
force_undirected: bool = False,
flow: str = 'source_to_target',
cosine: bool = False,
num_workers: int = 1,
) -> None:
self.k = k
self.loop = loop
self.force_undirected = force_undirected
self.flow = flow
self.cosine = cosine
self.num_workers = num_workers
def forward(self, data: Data) -> Data:
assert data.pos is not None
edge_index = torch_geometric.nn.knn_graph(
data.pos,
self.k,
data.batch,
loop=self.loop,
flow=self.flow,
cosine=self.cosine,
num_workers=self.num_workers,
)
if self.force_undirected:
edge_index = to_undirected(edge_index, num_nodes=data.num_nodes)
data.edge_index = edge_index
data.edge_attr = None
return data
def __repr__(self) -> str:
return f'{self.__class__.__name__}(k={self.k})'
|
