wehub-resource-sync
214 lines
6.9 KiB
Python
214 lines
6.9 KiB
Python
"""Torch Module for graph attention network layer using the aggregation
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primitives in cugraph-ops"""
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# pylint: disable=no-member, arguments-differ, invalid-name, too-many-arguments
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import torch
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from torch import nn
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from .cugraph_base import CuGraphBaseConv
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try:
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from pylibcugraphops.pytorch import SampledCSC, StaticCSC
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from pylibcugraphops.pytorch.operators import mha_gat_n2n as GATConvAgg
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HAS_PYLIBCUGRAPHOPS = True
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except ImportError:
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HAS_PYLIBCUGRAPHOPS = False
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class CuGraphGATConv(CuGraphBaseConv):
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r"""Graph attention layer from `Graph Attention Networks
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<https://arxiv.org/pdf/1710.10903.pdf>`__, with the sparse aggregation
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accelerated by cugraph-ops.
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See :class:`dgl.nn.pytorch.conv.GATConv` for mathematical model.
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This module depends on :code:`pylibcugraphops` package, which can be
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installed via :code:`conda install -c nvidia pylibcugraphops=23.04`.
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:code:`pylibcugraphops` 23.04 requires python 3.8.x or 3.10.x.
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.. note::
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This is an **experimental** feature.
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Parameters
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----------
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in_feats : int
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Input feature size.
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out_feats : int
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Output feature size.
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num_heads : int
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Number of heads in Multi-Head Attention.
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feat_drop : float, optional
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Dropout rate on feature. Defaults: ``0``.
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negative_slope : float, optional
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LeakyReLU angle of negative slope. Defaults: ``0.2``.
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residual : bool, optional
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If True, use residual connection. Defaults: ``False``.
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activation : callable activation function/layer or None, optional.
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If not None, applies an activation function to the updated node features.
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Default: ``None``.
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bias : bool, optional
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If True, learns a bias term. Defaults: ``True``.
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Examples
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--------
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>>> import dgl
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>>> import torch
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>>> from dgl.nn import CuGraphGATConv
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>>> device = 'cuda'
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>>> g = dgl.graph(([0,1,2,3,2,5], [1,2,3,4,0,3])).to(device)
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>>> g = dgl.add_self_loop(g)
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>>> feat = torch.ones(6, 10).to(device)
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>>> conv = CuGraphGATConv(10, 2, num_heads=3).to(device)
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>>> res = conv(g, feat)
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>>> res
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tensor([[[ 0.2340, 1.9226],
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[ 1.6477, -1.9986],
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[ 1.1138, -1.9302]],
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[[ 0.2340, 1.9226],
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[ 1.6477, -1.9986],
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[ 1.1138, -1.9302]],
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[[ 0.2340, 1.9226],
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[ 1.6477, -1.9986],
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[ 1.1138, -1.9302]],
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[[ 0.2340, 1.9226],
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[ 1.6477, -1.9986],
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[ 1.1138, -1.9302]],
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[[ 0.2340, 1.9226],
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[ 1.6477, -1.9986],
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[ 1.1138, -1.9302]],
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[[ 0.2340, 1.9226],
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[ 1.6477, -1.9986],
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[ 1.1138, -1.9302]]], device='cuda:0', grad_fn=<ViewBackward0>)
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"""
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MAX_IN_DEGREE_MFG = 200
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def __init__(
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self,
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in_feats,
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out_feats,
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num_heads,
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feat_drop=0.0,
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negative_slope=0.2,
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residual=False,
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activation=None,
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bias=True,
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):
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if HAS_PYLIBCUGRAPHOPS is False:
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raise ModuleNotFoundError(
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f"{self.__class__.__name__} requires pylibcugraphops=23.04. "
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f"Install via `conda install -c nvidia 'pylibcugraphops=23.04'`."
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f"pylibcugraphops requires Python 3.8 or 3.10."
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)
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super().__init__()
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self.in_feats = in_feats
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self.out_feats = out_feats
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self.num_heads = num_heads
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self.feat_drop = nn.Dropout(feat_drop)
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self.negative_slope = negative_slope
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self.activation = activation
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self.fc = nn.Linear(in_feats, out_feats * num_heads, bias=False)
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self.attn_weights = nn.Parameter(
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torch.Tensor(2 * num_heads * out_feats)
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)
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if bias:
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self.bias = nn.Parameter(torch.Tensor(num_heads * out_feats))
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else:
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self.register_buffer("bias", None)
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if residual:
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if in_feats == out_feats * num_heads:
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self.res_fc = nn.Identity()
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else:
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self.res_fc = nn.Linear(
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in_feats, out_feats * num_heads, bias=False
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)
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else:
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self.register_buffer("res_fc", None)
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self.reset_parameters()
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def reset_parameters(self):
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r"""Reinitialize learnable parameters."""
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gain = nn.init.calculate_gain("relu")
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nn.init.xavier_normal_(self.fc.weight, gain=gain)
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nn.init.xavier_normal_(
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self.attn_weights.view(2, self.num_heads, self.out_feats), gain=gain
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)
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if self.bias is not None:
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nn.init.zeros_(self.bias)
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if isinstance(self.res_fc, nn.Linear):
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self.res_fc.reset_parameters()
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def forward(self, g, feat, max_in_degree=None):
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r"""Forward computation.
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Parameters
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----------
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g : DGLGraph
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The graph.
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feat : torch.Tensor
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Input features of shape :math:`(N, D_{in})`.
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max_in_degree : int
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Maximum in-degree of destination nodes. It is only effective when
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:attr:`g` is a :class:`DGLBlock`, i.e., bipartite graph. When
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:attr:`g` is generated from a neighbor sampler, the value should be
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set to the corresponding :attr:`fanout`. If not given,
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:attr:`max_in_degree` will be calculated on-the-fly.
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Returns
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-------
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torch.Tensor
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The output feature of shape :math:`(N, H, D_{out})` where
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:math:`H` is the number of heads, and :math:`D_{out}` is size of
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output feature.
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"""
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offsets, indices, _ = g.adj_tensors("csc")
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if g.is_block:
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if max_in_degree is None:
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max_in_degree = g.in_degrees().max().item()
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if max_in_degree < self.MAX_IN_DEGREE_MFG:
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_graph = SampledCSC(
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offsets,
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indices,
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max_in_degree,
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g.num_src_nodes(),
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)
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else:
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offsets_fg = self.pad_offsets(offsets, g.num_src_nodes() + 1)
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_graph = StaticCSC(offsets_fg, indices)
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else:
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_graph = StaticCSC(offsets, indices)
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feat = self.feat_drop(feat)
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feat_transformed = self.fc(feat)
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out = GATConvAgg(
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feat_transformed,
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self.attn_weights,
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_graph,
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self.num_heads,
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"LeakyReLU",
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self.negative_slope,
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concat_heads=True,
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)[: g.num_dst_nodes()].view(-1, self.num_heads, self.out_feats)
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feat_dst = feat[: g.num_dst_nodes()]
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if self.res_fc is not None:
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out = out + self.res_fc(feat_dst).view(
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-1, self.num_heads, self.out_feats
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)
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if self.bias is not None:
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out = out + self.bias.view(-1, self.num_heads, self.out_feats)
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if self.activation is not None:
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out = self.activation(out)
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return out
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