Source code for torch_geometric.loader.cluster

import copy
import os.path as osp
import sys
from dataclasses import dataclass
from typing import List, Optional

import torch
from torch import Tensor

import torch_geometric.typing
from import Data
from torch_geometric.typing import pyg_lib
from torch_geometric.utils import index_sort, narrow, select, sort_edge_index
from import map_index
from torch_geometric.utils.sparse import index2ptr, ptr2index

class Partition:
    rowptr: Tensor
    col: Tensor
    partptr: Tensor
    node_perm: Tensor
    edge_perm: Tensor

[docs]class ClusterData( r"""Clusters/partitions a graph data object into multiple subgraphs, as motivated by the `"Cluster-GCN: An Efficient Algorithm for Training Deep and Large Graph Convolutional Networks" <>`_ paper. .. note:: The underlying METIS algorithm requires undirected graphs as input. Args: data ( The graph data object. num_parts (int): The number of partitions. recursive (bool, optional): If set to :obj:`True`, will use multilevel recursive bisection instead of multilevel k-way partitioning. (default: :obj:`False`) save_dir (str, optional): If set, will save the partitioned data to the :obj:`save_dir` directory for faster re-use. (default: :obj:`None`) log (bool, optional): If set to :obj:`False`, will not log any progress. (default: :obj:`True`) keep_inter_cluster_edges (bool, optional): If set to :obj:`True`, will keep inter-cluster edge connections. (default: :obj:`False`) """ def __init__( self, data, num_parts: int, recursive: bool = False, save_dir: Optional[str] = None, log: bool = True, keep_inter_cluster_edges: bool = False, ): assert data.edge_index is not None self.num_parts = num_parts self.recursive = recursive self.keep_inter_cluster_edges = keep_inter_cluster_edges recursive_str = '_recursive' if recursive else '' filename = f'metis_{num_parts}{recursive_str}.pt' path = osp.join(save_dir or '', filename) if save_dir is not None and osp.exists(path): self.partition = torch.load(path) else: if log: # pragma: no cover print('Computing METIS partitioning...', file=sys.stderr) cluster = self._metis(data.edge_index, data.num_nodes) self.partition = self._partition(data.edge_index, cluster) if save_dir is not None:, path) if log: # pragma: no cover print('Done!', file=sys.stderr) = self._permute_data(data, self.partition) def _metis(self, edge_index: Tensor, num_nodes: int) -> Tensor: # Computes a node-level partition assignment vector via METIS. # Calculate CSR representation: row, col = sort_edge_index(edge_index, num_nodes=num_nodes) rowptr = index2ptr(row, size=num_nodes) # Compute METIS partitioning: cluster: Optional[Tensor] = None if torch_geometric.typing.WITH_TORCH_SPARSE: try: cluster = torch.ops.torch_sparse.partition( rowptr.cpu(), col.cpu(), None, self.num_parts, self.recursive, ).to(edge_index.device) except (AttributeError, RuntimeError): pass if cluster is None and torch_geometric.typing.WITH_METIS: cluster = pyg_lib.partition.metis( rowptr.cpu(), col.cpu(), self.num_parts, recursive=self.recursive, ).to(edge_index.device) if cluster is None: raise ImportError(f"'{self.__class__.__name__}' requires either " f"'pyg-lib' or 'torch-sparse'") return cluster def _partition(self, edge_index: Tensor, cluster: Tensor) -> Partition: # Computes node-level and edge-level permutations and permutes the edge # connectivity accordingly: # Sort `cluster` and compute boundaries `partptr`: cluster, node_perm = index_sort(cluster, max_value=self.num_parts) partptr = index2ptr(cluster, size=self.num_parts) # Permute `edge_index` based on node permutation: edge_perm = torch.arange(edge_index.size(1), device=edge_index.device) arange = torch.empty_like(node_perm) arange[node_perm] = torch.arange(cluster.numel(), device=cluster.device) edge_index = arange[edge_index] # Compute final CSR representation: (row, col), edge_perm = sort_edge_index( edge_index, edge_attr=edge_perm, num_nodes=cluster.numel(), ) rowptr = index2ptr(row, size=cluster.numel()) return Partition(rowptr, col, partptr, node_perm, edge_perm) def _permute_data(self, data: Data, partition: Partition) -> Data: # Permute node-level and edge-level attributes according to the # calculated permutations in `Partition`: out = copy.copy(data) for key, value in data.items(): if key == 'edge_index': continue elif data.is_node_attr(key): cat_dim = data.__cat_dim__(key, value) out[key] = select(value, partition.node_perm, dim=cat_dim) elif data.is_edge_attr(key): cat_dim = data.__cat_dim__(key, value) out[key] = select(value, partition.edge_perm, dim=cat_dim) out.edge_index = None return out def __len__(self) -> int: return self.partition.partptr.numel() - 1 def __getitem__(self, idx: int) -> Data: node_start = int(self.partition.partptr[idx]) node_end = int(self.partition.partptr[idx + 1]) node_length = node_end - node_start rowptr = self.partition.rowptr[node_start:node_end + 1] edge_start = int(rowptr[0]) edge_end = int(rowptr[-1]) edge_length = edge_end - edge_start rowptr = rowptr - edge_start row = ptr2index(rowptr) col = self.partition.col[edge_start:edge_end] if not self.keep_inter_cluster_edges: edge_mask = (col >= node_start) & (col < node_end) row = row[edge_mask] col = col[edge_mask] - node_start out = copy.copy( for key, value in if key == 'num_nodes': out.num_nodes = node_length elif cat_dim =, value) out[key] = narrow(value, cat_dim, node_start, node_length) elif cat_dim =, value) out[key] = narrow(value, cat_dim, edge_start, edge_length) if not self.keep_inter_cluster_edges: out[key] = out[key][edge_mask] out.edge_index = torch.stack([row, col], dim=0) return out def __repr__(self) -> str: return f'{self.__class__.__name__}({self.num_parts})'
[docs]class ClusterLoader( r"""The data loader scheme from the `"Cluster-GCN: An Efficient Algorithm for Training Deep and Large Graph Convolutional Networks" <>`_ paper which merges partioned subgraphs and their between-cluster links from a large-scale graph data object to form a mini-batch. .. note:: Use :class:`~torch_geometric.loader.ClusterData` and :class:`~torch_geometric.loader.ClusterLoader` in conjunction to form mini-batches of clusters. For an example of using Cluster-GCN, see `examples/ < pytorch_geometric/blob/master/examples/>`_ or `examples/ < pytorch_geometric/blob/master/examples/>`_. Args: cluster_data (torch_geometric.loader.ClusterData): The already partioned data object. **kwargs (optional): Additional arguments of :class:``, such as :obj:`batch_size`, :obj:`shuffle`, :obj:`drop_last` or :obj:`num_workers`. """ def __init__(self, cluster_data, **kwargs): self.cluster_data = cluster_data iterator = range(len(cluster_data)) super().__init__(iterator, collate_fn=self._collate, **kwargs) def _collate(self, batch: List[int]) -> Data: if not isinstance(batch, torch.Tensor): batch = torch.tensor(batch) global_rowptr = self.cluster_data.partition.rowptr global_col = self.cluster_data.partition.col # Get all node-level and edge-level start and end indices for the # current mini-batch: node_start = self.cluster_data.partition.partptr[batch] node_end = self.cluster_data.partition.partptr[batch + 1] edge_start = global_rowptr[node_start] edge_end = global_rowptr[node_end] # Iterate over each partition in the batch and calculate new edge # connectivity. This is done by slicing the corresponding source and # destination indices for each partition and adjusting their indices to # start from zero: rows, cols, nodes, cumsum = [], [], [], 0 for i in range(batch.numel()): nodes.append(torch.arange(node_start[i], node_end[i])) rowptr = global_rowptr[node_start[i]:node_end[i] + 1] rowptr = rowptr - edge_start[i] row = ptr2index(rowptr) + cumsum col = global_col[edge_start[i]:edge_end[i]] rows.append(row) cols.append(col) cumsum += rowptr.numel() - 1 node =, dim=0) row =, dim=0) col =, dim=0) # Map `col` vector to valid entries and remove any entries that do not # connect two nodes within the same mini-batch: col, edge_mask = map_index(col, node) row = row[edge_mask] out = copy.copy( # Slice node-level and edge-level attributes according to its offsets: for key, value in if key == 'num_nodes': out.num_nodes = cumsum elif cat_dim =, value) out[key] =[ narrow(out[key], cat_dim, s, e - s) for s, e in zip(node_start, node_end) ], dim=cat_dim) elif cat_dim =, value) value =[ narrow(out[key], cat_dim, s, e - s) for s, e in zip(edge_start, edge_end) ], dim=cat_dim) out[key] = select(value, edge_mask, dim=cat_dim) out.edge_index = torch.stack([row, col], dim=0) return out