Files
2026-07-13 13:35:51 +08:00

588 lines
21 KiB
Python

import random
import numpy as np
import torch
import torch.multiprocessing as mp
import torch.nn as nn
import torch.nn.functional as F
from torch.multiprocessing import Queue
from torch.nn import init
def init_emb2pos_index(walk_length, window_size, batch_size):
"""select embedding of positive nodes from a batch of node embeddings
Return
------
index_emb_posu torch.LongTensor : the indices of u_embeddings
index_emb_posv torch.LongTensor : the indices of v_embeddings
Usage
-----
# emb_u.shape: [batch_size * walk_length, dim]
batch_emb2posu = torch.index_select(emb_u, 0, index_emb_posu)
"""
idx_list_u = []
idx_list_v = []
for b in range(batch_size):
for i in range(walk_length):
for j in range(i - window_size, i):
if j >= 0:
idx_list_u.append(j + b * walk_length)
idx_list_v.append(i + b * walk_length)
for j in range(i + 1, i + 1 + window_size):
if j < walk_length:
idx_list_u.append(j + b * walk_length)
idx_list_v.append(i + b * walk_length)
# [num_pos * batch_size]
index_emb_posu = torch.LongTensor(idx_list_u)
index_emb_posv = torch.LongTensor(idx_list_v)
return index_emb_posu, index_emb_posv
def init_emb2neg_index(walk_length, window_size, negative, batch_size):
"""select embedding of negative nodes from a batch of node embeddings
for fast negative sampling
Return
------
index_emb_negu torch.LongTensor : the indices of u_embeddings
index_emb_negv torch.LongTensor : the indices of v_embeddings
Usage
-----
# emb_u.shape: [batch_size * walk_length, dim]
batch_emb2negu = torch.index_select(emb_u, 0, index_emb_negu)
"""
idx_list_u = []
for b in range(batch_size):
for i in range(walk_length):
for j in range(i - window_size, i):
if j >= 0:
idx_list_u += [i + b * walk_length] * negative
for j in range(i + 1, i + 1 + window_size):
if j < walk_length:
idx_list_u += [i + b * walk_length] * negative
idx_list_v = (
list(range(batch_size * walk_length)) * negative * window_size * 2
)
random.shuffle(idx_list_v)
idx_list_v = idx_list_v[: len(idx_list_u)]
# [bs * walk_length * negative]
index_emb_negu = torch.LongTensor(idx_list_u)
index_emb_negv = torch.LongTensor(idx_list_v)
return index_emb_negu, index_emb_negv
def init_weight(walk_length, window_size, batch_size):
"""init context weight"""
weight = []
for b in range(batch_size):
for i in range(walk_length):
for j in range(i - window_size, i):
if j >= 0:
weight.append(1.0 - float(i - j - 1) / float(window_size))
for j in range(i + 1, i + 1 + window_size):
if j < walk_length:
weight.append(1.0 - float(j - i - 1) / float(window_size))
# [num_pos * batch_size]
return torch.Tensor(weight).unsqueeze(1)
def init_empty_grad(emb_dimension, walk_length, batch_size):
"""initialize gradient matrix"""
grad_u = torch.zeros((batch_size * walk_length, emb_dimension))
grad_v = torch.zeros((batch_size * walk_length, emb_dimension))
return grad_u, grad_v
def adam(grad, state_sum, nodes, lr, device, only_gpu):
"""calculate gradients according to adam"""
grad_sum = (grad * grad).mean(1)
if not only_gpu:
grad_sum = grad_sum.cpu()
state_sum.index_add_(0, nodes, grad_sum) # cpu
std = state_sum[nodes].to(device) # gpu
std_values = std.sqrt_().add_(1e-10).unsqueeze(1)
grad = lr * grad / std_values # gpu
return grad
def async_update(num_threads, model, queue):
"""asynchronous embedding update"""
torch.set_num_threads(num_threads)
while True:
(grad_u, grad_v, grad_v_neg, nodes, neg_nodes) = queue.get()
if grad_u is None:
return
with torch.no_grad():
model.u_embeddings.weight.data.index_add_(0, nodes.view(-1), grad_u)
model.v_embeddings.weight.data.index_add_(0, nodes.view(-1), grad_v)
if neg_nodes is not None:
model.v_embeddings.weight.data.index_add_(
0, neg_nodes.view(-1), grad_v_neg
)
class SkipGramModel(nn.Module):
"""Negative sampling based skip-gram"""
def __init__(
self,
emb_size,
emb_dimension,
walk_length,
window_size,
batch_size,
only_cpu,
only_gpu,
mix,
neg_weight,
negative,
lr,
lap_norm,
fast_neg,
record_loss,
norm,
use_context_weight,
async_update,
num_threads,
):
"""initialize embedding on CPU
Paremeters
----------
emb_size int : number of nodes
emb_dimension int : embedding dimension
walk_length int : number of nodes in a sequence
window_size int : context window size
batch_size int : number of node sequences in each batch
only_cpu bool : training with CPU
only_gpu bool : training with GPU
mix bool : mixed training with CPU and GPU
negative int : negative samples for each positve node pair
neg_weight float : negative weight
lr float : initial learning rate
lap_norm float : weight of laplacian normalization
fast_neg bool : do negative sampling inside a batch
record_loss bool : print the loss during training
norm bool : do normalizatin on the embedding after training
use_context_weight : give different weights to the nodes in a context window
async_update : asynchronous training
"""
super(SkipGramModel, self).__init__()
self.emb_size = emb_size
self.emb_dimension = emb_dimension
self.walk_length = walk_length
self.window_size = window_size
self.batch_size = batch_size
self.only_cpu = only_cpu
self.only_gpu = only_gpu
self.mixed_train = mix
self.neg_weight = neg_weight
self.negative = negative
self.lr = lr
self.lap_norm = lap_norm
self.fast_neg = fast_neg
self.record_loss = record_loss
self.norm = norm
self.use_context_weight = use_context_weight
self.async_update = async_update
self.num_threads = num_threads
# initialize the device as cpu
self.device = torch.device("cpu")
# content embedding
self.u_embeddings = nn.Embedding(
self.emb_size, self.emb_dimension, sparse=True
)
# context embedding
self.v_embeddings = nn.Embedding(
self.emb_size, self.emb_dimension, sparse=True
)
# initialze embedding
initrange = 1.0 / self.emb_dimension
init.uniform_(self.u_embeddings.weight.data, -initrange, initrange)
init.constant_(self.v_embeddings.weight.data, 0)
# lookup_table is used for fast sigmoid computing
self.lookup_table = torch.sigmoid(torch.arange(-6.01, 6.01, 0.01))
self.lookup_table[0] = 0.0
self.lookup_table[-1] = 1.0
if self.record_loss:
self.logsigmoid_table = torch.log(
torch.sigmoid(torch.arange(-6.01, 6.01, 0.01))
)
self.loss = []
# indexes to select positive/negative node pairs from batch_walks
self.index_emb_posu, self.index_emb_posv = init_emb2pos_index(
self.walk_length, self.window_size, self.batch_size
)
self.index_emb_negu, self.index_emb_negv = init_emb2neg_index(
self.walk_length, self.window_size, self.negative, self.batch_size
)
if self.use_context_weight:
self.context_weight = init_weight(
self.walk_length, self.window_size, self.batch_size
)
# adam
self.state_sum_u = torch.zeros(self.emb_size)
self.state_sum_v = torch.zeros(self.emb_size)
# gradients of nodes in batch_walks
self.grad_u, self.grad_v = init_empty_grad(
self.emb_dimension, self.walk_length, self.batch_size
)
def create_async_update(self):
"""Set up the async update subprocess."""
self.async_q = Queue(1)
self.async_p = mp.Process(
target=async_update, args=(self.num_threads, self, self.async_q)
)
self.async_p.start()
def finish_async_update(self):
"""Notify the async update subprocess to quit."""
self.async_q.put((None, None, None, None, None))
self.async_p.join()
def share_memory(self):
"""share the parameters across subprocesses"""
self.u_embeddings.weight.share_memory_()
self.v_embeddings.weight.share_memory_()
self.state_sum_u.share_memory_()
self.state_sum_v.share_memory_()
def set_device(self, gpu_id):
"""set gpu device"""
self.device = torch.device("cuda:%d" % gpu_id)
print("The device is", self.device)
self.lookup_table = self.lookup_table.to(self.device)
if self.record_loss:
self.logsigmoid_table = self.logsigmoid_table.to(self.device)
self.index_emb_posu = self.index_emb_posu.to(self.device)
self.index_emb_posv = self.index_emb_posv.to(self.device)
self.index_emb_negu = self.index_emb_negu.to(self.device)
self.index_emb_negv = self.index_emb_negv.to(self.device)
self.grad_u = self.grad_u.to(self.device)
self.grad_v = self.grad_v.to(self.device)
if self.use_context_weight:
self.context_weight = self.context_weight.to(self.device)
def all_to_device(self, gpu_id):
"""move all of the parameters to a single GPU"""
self.device = torch.device("cuda:%d" % gpu_id)
self.set_device(gpu_id)
self.u_embeddings = self.u_embeddings.cuda(gpu_id)
self.v_embeddings = self.v_embeddings.cuda(gpu_id)
self.state_sum_u = self.state_sum_u.to(self.device)
self.state_sum_v = self.state_sum_v.to(self.device)
def fast_sigmoid(self, score):
"""do fast sigmoid by looking up in a pre-defined table"""
idx = torch.floor((score + 6.01) / 0.01).long()
return self.lookup_table[idx]
def fast_logsigmoid(self, score):
"""do fast logsigmoid by looking up in a pre-defined table"""
idx = torch.floor((score + 6.01) / 0.01).long()
return self.logsigmoid_table[idx]
def fast_learn(self, batch_walks, neg_nodes=None):
"""Learn a batch of random walks in a fast way. It has the following features:
1. It calculating the gradients directly without the forward operation.
2. It does sigmoid by a looking up table.
Specifically, for each positive/negative node pair (i,j), the updating procedure is as following:
score = self.fast_sigmoid(u_embedding[i].dot(v_embedding[j]))
# label = 1 for positive samples; label = 0 for negative samples.
u_embedding[i] += (label - score) * v_embedding[j]
v_embedding[i] += (label - score) * u_embedding[j]
Parameters
----------
batch_walks list : a list of node sequnces
lr float : current learning rate
neg_nodes torch.LongTensor : a long tensor of sampled true negative nodes. If neg_nodes is None,
then do negative sampling randomly from the nodes in batch_walks as an alternative.
Usage example
-------------
batch_walks = [torch.LongTensor([1,2,3,4]),
torch.LongTensor([2,3,4,2])])
lr = 0.01
neg_nodes = None
"""
lr = self.lr
# [batch_size, walk_length]
if isinstance(batch_walks, list):
nodes = torch.stack(batch_walks)
elif isinstance(batch_walks, torch.LongTensor):
nodes = batch_walks
if self.only_gpu:
nodes = nodes.to(self.device)
if neg_nodes is not None:
neg_nodes = neg_nodes.to(self.device)
emb_u = (
self.u_embeddings(nodes)
.view(-1, self.emb_dimension)
.to(self.device)
)
emb_v = (
self.v_embeddings(nodes)
.view(-1, self.emb_dimension)
.to(self.device)
)
## Postive
bs = len(batch_walks)
if bs < self.batch_size:
index_emb_posu, index_emb_posv = init_emb2pos_index(
self.walk_length, self.window_size, bs
)
index_emb_posu = index_emb_posu.to(self.device)
index_emb_posv = index_emb_posv.to(self.device)
else:
index_emb_posu = self.index_emb_posu
index_emb_posv = self.index_emb_posv
# num_pos: the number of positive node pairs generated by a single walk sequence
# [batch_size * num_pos, dim]
emb_pos_u = torch.index_select(emb_u, 0, index_emb_posu)
emb_pos_v = torch.index_select(emb_v, 0, index_emb_posv)
pos_score = torch.sum(torch.mul(emb_pos_u, emb_pos_v), dim=1)
pos_score = torch.clamp(pos_score, max=6, min=-6)
# [batch_size * num_pos, 1]
score = (1 - self.fast_sigmoid(pos_score)).unsqueeze(1)
if self.record_loss:
self.loss.append(torch.mean(self.fast_logsigmoid(pos_score)).item())
# [batch_size * num_pos, dim]
if self.lap_norm > 0:
grad_u_pos = score * emb_pos_v + self.lap_norm * (
emb_pos_v - emb_pos_u
)
grad_v_pos = score * emb_pos_u + self.lap_norm * (
emb_pos_u - emb_pos_v
)
else:
grad_u_pos = score * emb_pos_v
grad_v_pos = score * emb_pos_u
if self.use_context_weight:
if bs < self.batch_size:
context_weight = init_weight(
self.walk_length, self.window_size, bs
).to(self.device)
else:
context_weight = self.context_weight
grad_u_pos *= context_weight
grad_v_pos *= context_weight
# [batch_size * walk_length, dim]
if bs < self.batch_size:
grad_u, grad_v = init_empty_grad(
self.emb_dimension, self.walk_length, bs
)
grad_u = grad_u.to(self.device)
grad_v = grad_v.to(self.device)
else:
self.grad_u = self.grad_u.to(self.device)
self.grad_u.zero_()
self.grad_v = self.grad_v.to(self.device)
self.grad_v.zero_()
grad_u = self.grad_u
grad_v = self.grad_v
grad_u.index_add_(0, index_emb_posu, grad_u_pos)
grad_v.index_add_(0, index_emb_posv, grad_v_pos)
## Negative
if bs < self.batch_size:
index_emb_negu, index_emb_negv = init_emb2neg_index(
self.walk_length, self.window_size, self.negative, bs
)
index_emb_negu = index_emb_negu.to(self.device)
index_emb_negv = index_emb_negv.to(self.device)
else:
index_emb_negu = self.index_emb_negu
index_emb_negv = self.index_emb_negv
emb_neg_u = torch.index_select(emb_u, 0, index_emb_negu)
if neg_nodes is None:
emb_neg_v = torch.index_select(emb_v, 0, index_emb_negv)
else:
emb_neg_v = self.v_embeddings.weight[neg_nodes].to(self.device)
# [batch_size * walk_length * negative, dim]
neg_score = torch.sum(torch.mul(emb_neg_u, emb_neg_v), dim=1)
neg_score = torch.clamp(neg_score, max=6, min=-6)
# [batch_size * walk_length * negative, 1]
score = -self.fast_sigmoid(neg_score).unsqueeze(1)
if self.record_loss:
self.loss.append(
self.negative
* self.neg_weight
* torch.mean(self.fast_logsigmoid(-neg_score)).item()
)
grad_u_neg = self.neg_weight * score * emb_neg_v
grad_v_neg = self.neg_weight * score * emb_neg_u
grad_u.index_add_(0, index_emb_negu, grad_u_neg)
if neg_nodes is None:
grad_v.index_add_(0, index_emb_negv, grad_v_neg)
## Update
nodes = nodes.view(-1)
# use adam optimizer
grad_u = adam(
grad_u, self.state_sum_u, nodes, lr, self.device, self.only_gpu
)
grad_v = adam(
grad_v, self.state_sum_v, nodes, lr, self.device, self.only_gpu
)
if neg_nodes is not None:
grad_v_neg = adam(
grad_v_neg,
self.state_sum_v,
neg_nodes,
lr,
self.device,
self.only_gpu,
)
if self.mixed_train:
grad_u = grad_u.cpu()
grad_v = grad_v.cpu()
if neg_nodes is not None:
grad_v_neg = grad_v_neg.cpu()
else:
grad_v_neg = None
if self.async_update:
grad_u.share_memory_()
grad_v.share_memory_()
nodes.share_memory_()
if neg_nodes is not None:
neg_nodes.share_memory_()
grad_v_neg.share_memory_()
self.async_q.put((grad_u, grad_v, grad_v_neg, nodes, neg_nodes))
if not self.async_update:
self.u_embeddings.weight.data.index_add_(0, nodes.view(-1), grad_u)
self.v_embeddings.weight.data.index_add_(0, nodes.view(-1), grad_v)
if neg_nodes is not None:
self.v_embeddings.weight.data.index_add_(
0, neg_nodes.view(-1), grad_v_neg
)
return
def forward(self, pos_u, pos_v, neg_v):
"""Do forward and backward. It is designed for future use."""
emb_u = self.u_embeddings(pos_u)
emb_v = self.v_embeddings(pos_v)
emb_neg_v = self.v_embeddings(neg_v)
score = torch.sum(torch.mul(emb_u, emb_v), dim=1)
score = torch.clamp(score, max=6, min=-6)
score = -F.logsigmoid(score)
neg_score = torch.bmm(emb_neg_v, emb_u.unsqueeze(2)).squeeze()
neg_score = torch.clamp(neg_score, max=6, min=-6)
neg_score = -torch.sum(F.logsigmoid(-neg_score), dim=1)
# return torch.mean(score + neg_score)
return torch.sum(score), torch.sum(neg_score)
def save_embedding(self, dataset, file_name):
"""Write embedding to local file. Only used when node ids are numbers.
Parameter
---------
dataset DeepwalkDataset : the dataset
file_name str : the file name
"""
embedding = self.u_embeddings.weight.cpu().data.numpy()
if self.norm:
embedding /= np.sqrt(np.sum(embedding * embedding, 1)).reshape(
-1, 1
)
np.save(file_name, embedding)
def save_embedding_pt(self, dataset, file_name):
"""For ogb leaderboard."""
try:
max_node_id = max(dataset.node2id.keys())
if max_node_id + 1 != self.emb_size:
print("WARNING: The node ids are not serial.")
embedding = torch.zeros(max_node_id + 1, self.emb_dimension)
index = torch.LongTensor(
list(
map(
lambda id: dataset.id2node[id],
list(range(self.emb_size)),
)
)
)
embedding.index_add_(0, index, self.u_embeddings.weight.cpu().data)
if self.norm:
embedding /= torch.sqrt(
torch.sum(embedding.mul(embedding), 1) + 1e-6
).unsqueeze(1)
torch.save(embedding, file_name)
except:
self.save_embedding_pt_dgl_graph(dataset, file_name)
def save_embedding_pt_dgl_graph(self, dataset, file_name):
"""For ogb leaderboard"""
embedding = torch.zeros_like(self.u_embeddings.weight.cpu().data)
valid_seeds = torch.LongTensor(dataset.valid_seeds)
valid_embedding = self.u_embeddings.weight.cpu().data.index_select(
0, valid_seeds
)
embedding.index_add_(0, valid_seeds, valid_embedding)
if self.norm:
embedding /= torch.sqrt(
torch.sum(embedding.mul(embedding), 1) + 1e-6
).unsqueeze(1)
torch.save(embedding, file_name)
def save_embedding_txt(self, dataset, file_name):
"""Write embedding to local file. For future use.
Parameter
---------
dataset DeepwalkDataset : the dataset
file_name str : the file name
"""
embedding = self.u_embeddings.weight.cpu().data.numpy()
if self.norm:
embedding /= np.sqrt(np.sum(embedding * embedding, 1)).reshape(
-1, 1
)
with open(file_name, "w") as f:
f.write("%d %d\n" % (self.emb_size, self.emb_dimension))
for wid in range(self.emb_size):
e = " ".join(map(lambda x: str(x), embedding[wid]))
f.write("%s %s\n" % (str(dataset.id2node[wid]), e))