来源：
MUSE: Parallel Multi-Scale Attention for Sequence to Sequence Learning
相关工作：
#自注意力机制 #卷积神经网络 #动态卷积 #局部注意力 #并行计算
创新点：
贡献：
-
并行多尺度注意力机制：
- MUSE引入了并行多尺度注意力机制，该机制同时捕获序列数据中的长距离和短距离语言结构。这是通过对序列进行不同尺度的并行编码来实现的，利用自注意力和逐点变换。
-
结合卷积和自注意力：
- 为了解决自注意力在处理长序列时可能忽略局部信息的问题，MUSE模型将卷积操作和自注意力结合起来，以更有效地学习序列的局部和全局特征。
-
共享投影空间：
- 文章强调了在自注意力和卷积操作中使用共享投影空间的重要性。这种设计使得两种操作能够在相同的隐藏空间中进行，从而有助于整合局部和全局特征表示。
-
动态卷积核选择：
- MUSE引入了一种门控机制，用于自动选择不同卷积单元的权重，这允许模型动态地选择最适合当前层的卷积核大小。
代码：
python
# ---------------------------------------
# 论文: MUSE: PARALLEL MULTI-SCALE ATTENTION FOR SEQUENCE TO SEQUENCE LEARNING (arxiv 2019)
# ---------------------------------------
import numpy as np
import torch
from torch import nn
from torch.nn import init
class Depth_Pointwise_Conv1d(nn.Module):
def __init__(self, in_ch, out_ch, k):
super().__init__()
if (k == 1):
self.depth_conv = nn.Identity()
else:
self.depth_conv = nn.Conv1d(
in_channels=in_ch,
out_channels=in_ch,
kernel_size=k,
groups=in_ch,
padding=k // 2
)
self.pointwise_conv = nn.Conv1d(
in_channels=in_ch,
out_channels=out_ch,
kernel_size=1,
groups=1
)
def forward(self, x):
out = self.pointwise_conv(self.depth_conv(x))
return out
class MUSEAttention(nn.Module):
def __init__(self, d_model, d_k, d_v, h, dropout=.1):
super(MUSEAttention, self).__init__()
self.fc_q = nn.Linear(d_model, h * d_k)
self.fc_k = nn.Linear(d_model, h * d_k)
self.fc_v = nn.Linear(d_model, h * d_v)
self.fc_o = nn.Linear(h * d_v, d_model)
self.dropout = nn.Dropout(dropout)
self.conv1 = Depth_Pointwise_Conv1d(h * d_v, d_model, 1)
self.conv3 = Depth_Pointwise_Conv1d(h * d_v, d_model, 3)
self.conv5 = Depth_Pointwise_Conv1d(h * d_v, d_model, 5)
self.dy_paras = nn.Parameter(torch.ones(3))
self.softmax = nn.Softmax(-1)
self.d_model = d_model
self.d_k = d_k
self.d_v = d_v
self.h = h
self.init_weights()
def init_weights(self):
for m in self.modules():
if isinstance(m, nn.Conv2d):
init.kaiming_normal_(m.weight, mode='fan_out')
if m.bias is not None:
init.constant_(m.bias, 0)
elif isinstance(m, nn.BatchNorm2d):
init.constant_(m.weight, 1)
init.constant_(m.bias, 0)
elif isinstance(m, nn.Linear):
init.normal_(m.weight, std=0.001)
if m.bias is not None:
init.constant_(m.bias, 0)
def forward(self, queries, keys, values, attention_mask=None, attention_weights=None):
# Self Attention
b_s, nq = queries.shape[:2]
nk = keys.shape[1]
q = self.fc_q(queries).view(b_s, nq, self.h, self.d_k).permute(0, 2, 1, 3) # (b_s, h, nq, d_k)
k = self.fc_k(keys).view(b_s, nk, self.h, self.d_k).permute(0, 2, 3, 1) # (b_s, h, d_k, nk)
v = self.fc_v(values).view(b_s, nk, self.h, self.d_v).permute(0, 2, 1, 3) # (b_s, h, nk, d_v)
att = torch.matmul(q, k) / np.sqrt(self.d_k) # (b_s, h, nq, nk)
if attention_weights is not None:
att = att * attention_weights
if attention_mask is not None:
att = att.masked_fill(attention_mask, -np.inf)
att = torch.softmax(att, -1)
att = self.dropout(att)
out = torch.matmul(att, v).permute(0, 2, 1, 3).contiguous().view(b_s, nq, self.h * self.d_v) # (b_s, nq, h*d_v)
out = self.fc_o(out) # (b_s, nq, d_model)
v2 = v.permute(0, 1, 3, 2).contiguous().view(b_s, -1, nk) # bs,dim,n
self.dy_paras = nn.Parameter(self.softmax(self.dy_paras))
out2 = self.dy_paras[0] * self.conv1(v2) + self.dy_paras[1] * self.conv3(v2) + self.dy_paras[2] * self.conv5(v2)
out2 = out2.permute(0, 2, 1) # bs.n.dim
out = out + out2
return out
# 输入 B N C, 输出 B N Cif __name__ == '__main__':
block = MUSEAttention(d_model=32, d_k=32, d_v=32, h=8).cuda()
print("开始运行")
input = torch.rand(3, 64, 32).cuda()
output = block(input, input, input)
print(input.size(), output.size())
print('结束运行')