# Source code for dgllife.model.readout.weave_readout

```
# -*- coding: utf-8 -*-
#
# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: Apache-2.0
#
# Readout for Weave
#
# pylint: disable= no-member, arguments-differ, invalid-name
import dgl
import torch
import torch.nn as nn
from torch.distributions import Normal
__all__ = ['WeaveGather']
# pylint: disable=W0221, E1101, E1102
[docs]class WeaveGather(nn.Module):
r"""Readout in Weave
Parameters
----------
node_in_feats : int
Size for the input node features.
gaussian_expand : bool
Whether to expand each dimension of node features by gaussian histogram.
Default to True.
gaussian_memberships : list of 2-tuples
For each tuple, the first and second element separately specifies the mean
and std for constructing a normal distribution. This argument comes into
effect only when ``gaussian_expand==True``. By default, we set this to be
``[(-1.645, 0.283), (-1.080, 0.170), (-0.739, 0.134), (-0.468, 0.118),
(-0.228, 0.114), (0., 0.114), (0.228, 0.114), (0.468, 0.118),
(0.739, 0.134), (1.080, 0.170), (1.645, 0.283)]``.
activation : callable
Activation function to apply. Default to tanh.
"""
def __init__(self,
node_in_feats,
gaussian_expand=True,
gaussian_memberships=None,
activation=nn.Tanh()):
super(WeaveGather, self).__init__()
self.gaussian_expand = gaussian_expand
if gaussian_expand:
if gaussian_memberships is None:
gaussian_memberships = [
(-1.645, 0.283), (-1.080, 0.170), (-0.739, 0.134), (-0.468, 0.118),
(-0.228, 0.114), (0., 0.114), (0.228, 0.114), (0.468, 0.118),
(0.739, 0.134), (1.080, 0.170), (1.645, 0.283)]
means, stds = map(list, zip(*gaussian_memberships))
self.means = nn.ParameterList([
nn.Parameter(torch.tensor(value), requires_grad=False)
for value in means
])
self.stds = nn.ParameterList([
nn.Parameter(torch.tensor(value), requires_grad=False)
for value in stds
])
self.to_out = nn.Linear(node_in_feats * len(self.means), node_in_feats)
self.activation = activation
[docs] def gaussian_histogram(self, node_feats):
r"""Constructs a gaussian histogram to capture the distribution of features
Parameters
----------
node_feats : float32 tensor of shape (V, node_in_feats)
Input node features. V for the number of nodes in the batch of graphs.
Returns
-------
float32 tensor of shape (V, node_in_feats * len(self.means))
Updated node representations
"""
gaussian_dists = [Normal(self.means[i], self.stds[i])
for i in range(len(self.means))]
max_log_probs = [gaussian_dists[i].log_prob(self.means[i])
for i in range(len(self.means))]
# Normalize the probabilities by the maximum point-wise probabilities,
# whose results will be in range [0, 1]. Note that division of probabilities
# is equivalent to subtraction of log probabilities and the latter one is cheaper.
log_probs = [gaussian_dists[i].log_prob(node_feats) - max_log_probs[i]
for i in range(len(self.means))]
probs = torch.stack(log_probs, dim=2).exp() # (V, node_in_feats, len(self.means))
# Add a bias to avoid numerical issues in division
probs = probs + 1e-7
# Normalize the probabilities across all Gaussian distributions
probs = probs / probs.sum(2, keepdim=True)
return probs.reshape(node_feats.shape[0],
node_feats.shape[1] * len(self.means))
[docs] def forward(self, g, node_feats):
r"""Computes graph representations out of node representations.
Parameters
----------
g : DGLGraph
DGLGraph for a batch of graphs.
node_feats : float32 tensor of shape (V, node_in_feats)
Input node features. V for the number of nodes in the batch of graphs.
Returns
-------
g_feats : float32 tensor of shape (G, node_in_feats)
Output graph representations. G for the number of graphs in the batch.
"""
if self.gaussian_expand:
node_feats = self.gaussian_histogram(node_feats)
with g.local_scope():
g.ndata['h'] = node_feats
g_feats = dgl.sum_nodes(g, 'h')
if self.gaussian_expand:
g_feats = self.to_out(g_feats)
if self.activation is not None:
g_feats = self.activation(g_feats)
return g_feats
```