diff --git a/fastNLP/modules/aggregation/self_attention.py b/fastNLP/modules/aggregation/self_attention.py index 4155d708..d750ea54 100644 --- a/fastNLP/modules/aggregation/self_attention.py +++ b/fastNLP/modules/aggregation/self_attention.py @@ -5,6 +5,8 @@ import torch.nn.functional as F from fastNLP.modules.utils import initial_parameter + + class SelfAttention(nn.Module): """ Self Attention Module. @@ -15,57 +17,53 @@ class SelfAttention(nn.Module): num_vec: int, the number of encoded vectors """ - def __init__(self, input_size, dim=10, num_vec=10 ,drop = 0.5 ,initial_method =None): + def __init__(self, input_size, attention_unit=350, attention_hops=10, drop=0.5, initial_method=None, + use_cuda=False): super(SelfAttention, self).__init__() - # self.W_s1 = nn.Parameter(torch.randn(dim, input_size), requires_grad=True) - # self.W_s2 = nn.Parameter(torch.randn(num_vec, dim), requires_grad=True) - self.attention_hops = num_vec - self.ws1 = nn.Linear(input_size, dim, bias=False) - self.ws2 = nn.Linear(dim, num_vec, bias=False) + self.attention_hops = attention_hops + self.ws1 = nn.Linear(input_size, attention_unit, bias=False) + self.ws2 = nn.Linear(attention_unit, attention_hops, bias=False) + if use_cuda: + self.I = Variable(torch.eye(attention_hops).cuda(), requires_grad=False) + else: + self.I = Variable(torch.eye(attention_hops), requires_grad=False) + self.I_origin = self.I self.drop = nn.Dropout(drop) - self.softmax = nn.Softmax(dim=2) self.tanh = nn.Tanh() initial_parameter(self, initial_method) - def penalization(self, A): + + def penalization(self, attention): """ compute the penalization term for attention module """ - if self.W_s1.is_cuda: - I = Variable(torch.eye(A.size(1)).cuda(), requires_grad=False) - else: - I = Variable(torch.eye(A.size(1)), requires_grad=False) - M = torch.matmul(A, torch.transpose(A, 1, 2)) - I - M = M.view(M.size(0), -1) - return torch.sum(M ** 2, dim=1) - - def forward(self, outp ,inp): - # the following code can not be use because some word are padding ,these is not such module! + baz = attention.size(0) + size = self.I.size() + if len(size) != 3 or size[0] != baz: + self.I = self.I_origin.expand(baz, -1, -1) + attentionT = torch.transpose(attention, 1, 2).contiguous() + mat = torch.bmm(attention, attentionT) - self.I[:attention.size(0)] + ret = (torch.sum(torch.sum((mat ** 2), 2), 1).squeeze() + 1e-10) ** 0.5 + return torch.sum(ret) / size[0] - # inter = self.tanh(torch.matmul(self.W_s1, torch.transpose(x, 1, 2))) # [] - # A = self.softmax(torch.matmul(self.W_s2, inter)) - # out = torch.matmul(A, x) - # out = out.view(out.size(0), -1) - # penalty = self.penalization(A) - # return out, penalty - outp = outp.contiguous() - size = outp.size() # [bsz, len, nhid] + def forward(self, input, input_origin): + """ + :param input: the matrix to do attention. [baz, senLen, h_dim] + :param inp: then token index include pad token( 0 ) [baz , senLen] + :return output1: the input matrix after attention operation [baz, multi-head , h_dim] + :return output2: the attention penalty term, a scalar [1] + """ + input = input.contiguous() + size = input.size() # [bsz, len, nhid] - compressed_embeddings = outp.view(-1, size[2]) # [bsz*len, nhid*2] - transformed_inp = torch.transpose(inp, 0, 1).contiguous() # [bsz, len] - transformed_inp = transformed_inp.view(size[0], 1, size[1]) # [bsz, 1, len] - concatenated_inp = [transformed_inp for i in range(self.attention_hops)] - concatenated_inp = torch.cat(concatenated_inp, 1) # [bsz, hop, len] - hbar = self.tanh(self.ws1(self.drop(compressed_embeddings))) # [bsz*len, attention-unit] - attention = self.ws2(hbar).view(size[0], size[1], -1) # [bsz, len, hop] - attention = torch.transpose(attention, 1, 2).contiguous() # [bsz, hop, len] - penalized_alphas = attention + ( - -10000 * (concatenated_inp == 0).float()) - # [bsz, hop, len] + [bsz, hop, len] - attention = self.softmax(penalized_alphas.view(-1, size[1])) # [bsz*hop, len] - attention = attention.view(size[0], self.attention_hops, size[1]) # [bsz, hop, len] - return torch.bmm(attention, outp), attention # output --> [baz ,hop ,nhid] + input_origin = input_origin.expand(self.attention_hops, -1, -1) # [hops,baz, len] + input_origin = input_origin.transpose(0, 1).contiguous() # [baz, hops,len] + y1 = self.tanh(self.ws1(self.drop(input))) # [baz,len,dim] -->[bsz,len, attention-unit] + attention = self.ws2(y1).transpose(1,2).contiguous() # [bsz,len, attention-unit]--> [bsz, len, hop]--> [baz,hop,len] + attention = attention + (-999999 * (input_origin == 0).float()) # remove the weight on padding token. + attention = F.softmax(attention,2) # [baz ,hop, len] + return torch.bmm(attention, input), self.penalization(attention) # output1 --> [baz ,hop ,nhid]