Update multiheadAttention.py
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topduke
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@ -9,214 +9,6 @@ from paddle.nn.initializer import XavierNormal as xavier_normal_
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zeros_ = constant_(value=0.)
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ones_ = constant_(value=1.)
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class MultiheadAttention(nn.Layer):
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r"""Allows the model to jointly attend to information
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from different representation subspaces.
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See reference: Attention Is All You Need
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.. math::
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\text{MultiHead}(Q, K, V) = \text{Concat}(head_1,\dots,head_h)W^O
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\text{where} head_i = \text{Attention}(QW_i^Q, KW_i^K, VW_i^V)
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Args:
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embed_dim: total dimension of the model
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num_heads: parallel attention layers, or heads
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Examples::
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>>> multihead_attn = nn.MultiheadAttention(embed_dim, num_heads)
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>>> attn_output, attn_output_weights = multihead_attn(query, key, value)
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"""
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def __init__(self, embed_dim, num_heads, dropout=0., bias=True, add_bias_kv=False, add_zero_attn=False):
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super(MultiheadAttention, self).__init__()
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self.embed_dim = embed_dim
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self.num_heads = num_heads
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self.dropout = dropout
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self.head_dim = embed_dim // num_heads
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assert self.head_dim * num_heads == self.embed_dim, "embed_dim must be divisible by num_heads"
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self.scaling = self.head_dim ** -0.5
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self.out_proj = Linear(embed_dim, embed_dim, bias_attr=bias)
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if add_bias_kv:
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self.bias_k = self.create_parameter(
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shape=(1, 1, embed_dim), default_initializer=zeros_)
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self.add_parameter("bias_k", self.bias_k)
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self.bias_v = self.create_parameter(
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shape=(1, 1, embed_dim), default_initializer=zeros_)
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self.add_parameter("bias_v", self.bias_v)
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else:
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self.bias_k = self.bias_v = None
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self.add_zero_attn = add_zero_attn
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self._reset_parameters()
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self.conv1 = paddle.nn.Conv2D(in_channels=embed_dim, out_channels=embed_dim, kernel_size=(1, 1))
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self.conv2 = paddle.nn.Conv2D(in_channels=embed_dim, out_channels=embed_dim * 2, kernel_size=(1, 1))
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self.conv3 = paddle.nn.Conv2D(in_channels=embed_dim, out_channels=embed_dim * 3, kernel_size=(1, 1))
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def _reset_parameters(self):
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xavier_uniform_(self.out_proj.weight)
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if self.bias_k is not None:
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xavier_normal_(self.bias_k)
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if self.bias_v is not None:
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xavier_normal_(self.bias_v)
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def forward(self, query, key, value, key_padding_mask=None, incremental_state=None,
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need_weights=True, static_kv=False, attn_mask=None, qkv_ = [False,False,False]):
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"""
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Inputs of forward function
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query: [target length, batch size, embed dim]
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key: [sequence length, batch size, embed dim]
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value: [sequence length, batch size, embed dim]
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key_padding_mask: if True, mask padding based on batch size
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incremental_state: if provided, previous time steps are cashed
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need_weights: output attn_output_weights
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static_kv: key and value are static
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Outputs of forward function
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attn_output: [target length, batch size, embed dim]
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attn_output_weights: [batch size, target length, sequence length]
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"""
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qkv_same = qkv_[0]
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kv_same = qkv_[1]
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tgt_len, bsz, embed_dim = query.shape
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assert embed_dim == self.embed_dim
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assert list(query.shape) == [tgt_len, bsz, embed_dim]
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assert key.shape == value.shape
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if qkv_same:
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# self-attention
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q, k, v = self._in_proj_qkv(query)
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elif kv_same:
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# encoder-decoder attention
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q = self._in_proj_q(query)
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if key is None:
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assert value is None
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k = v = None
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else:
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k, v = self._in_proj_kv(key)
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else:
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q = self._in_proj_q(query)
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k = self._in_proj_k(key)
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v = self._in_proj_v(value)
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q *= self.scaling
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if self.bias_k is not None:
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assert self.bias_v is not None
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self.bias_k = paddle.concat([self.bias_k for i in range(bsz)],axis=1)
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self.bias_v = paddle.concat([self.bias_v for i in range(bsz)],axis=1)
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k = paddle.concat([k, self.bias_k])
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v = paddle.concat([v, self.bias_v])
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if attn_mask is not None:
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attn_mask = paddle.concat([attn_mask, paddle.zeros([attn_mask.shape[0], 1],dtype=attn_mask.dtype)], axis=1)
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if key_padding_mask is not None:
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key_padding_mask = paddle.concat(
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[key_padding_mask,paddle.zeros([key_padding_mask.shape[0], 1],dtype=key_padding_mask.dtype)], axis=1)
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q = q.reshape([tgt_len, bsz * self.num_heads, self.head_dim]).transpose([1, 0, 2])
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if k is not None:
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k = k.reshape([-1, bsz * self.num_heads, self.head_dim]).transpose([1, 0, 2])
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if v is not None:
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v = v.reshape([-1, bsz * self.num_heads, self.head_dim]).transpose([1, 0, 2])
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src_len = k.shape[1]
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if key_padding_mask is not None:
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assert key_padding_mask.shape[0] == bsz
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assert key_padding_mask.shape[1] == src_len
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if self.add_zero_attn:
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src_len += 1
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k = paddle.concat([k, paddle.zeros((k.shape[0], 1) + k.shape[2:],dtype=k.dtype)], axis=1)
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v = paddle.concat([v, paddle.zeros((v.shape[0], 1) + v.shape[2:],dtype=v.dtype)], axis=1)
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if attn_mask is not None:
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attn_mask = paddle.concat([attn_mask, paddle.zeros([attn_mask.shape[0], 1],dtype=attn_mask.dtype)], axis=1)
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if key_padding_mask is not None:
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key_padding_mask = paddle.concat(
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[key_padding_mask, paddle.zeros([key_padding_mask.shape[0], 1],dtype=key_padding_mask.dtype)], axis=1)
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attn_output_weights = paddle.bmm(q, k.transpose([0,2,1]))
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assert list(attn_output_weights.shape) == [bsz * self.num_heads, tgt_len, src_len]
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if attn_mask is not None:
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attn_mask = attn_mask.unsqueeze(0)
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attn_output_weights += attn_mask
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if key_padding_mask is not None:
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attn_output_weights = attn_output_weights.reshape([bsz, self.num_heads, tgt_len, src_len])
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key = key_padding_mask.unsqueeze(1).unsqueeze(2).astype('float32')
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y = paddle.full(shape=key.shape, dtype='float32', fill_value='-inf')
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y = paddle.where(key==0.,key, y)
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attn_output_weights += y
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attn_output_weights = attn_output_weights.reshape([bsz*self.num_heads, tgt_len, src_len])
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attn_output_weights = F.softmax(
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attn_output_weights.astype('float32'), axis=-1,
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dtype=paddle.float32 if attn_output_weights.dtype == paddle.float16 else attn_output_weights.dtype)
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attn_output_weights = F.dropout(attn_output_weights, p=self.dropout, training=self.training)
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attn_output = paddle.bmm(attn_output_weights, v)
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assert list(attn_output.shape) == [bsz * self.num_heads, tgt_len, self.head_dim]
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attn_output = attn_output.transpose([1, 0,2]).reshape([tgt_len, bsz, embed_dim])
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attn_output = self.out_proj(attn_output)
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if need_weights:
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# average attention weights over heads
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attn_output_weights = attn_output_weights.reshape([bsz, self.num_heads, tgt_len, src_len])
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attn_output_weights = attn_output_weights.sum(axis=1) / self.num_heads
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else:
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attn_output_weights = None
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return attn_output, attn_output_weights
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def _in_proj_qkv(self, query):
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query = query.transpose([1, 2, 0])
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query = paddle.unsqueeze(query, axis=2)
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res = self.conv3(query)
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res = paddle.squeeze(res, axis=2)
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res = res.transpose([2, 0, 1])
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return res.chunk(3, axis=-1)
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def _in_proj_kv(self, key):
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key = key.transpose([1, 2, 0])
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key = paddle.unsqueeze(key, axis=2)
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res = self.conv2(key)
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res = paddle.squeeze(res, axis=2)
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res = res.transpose([2, 0, 1])
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return res.chunk(2, axis=-1)
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def _in_proj_q(self, query):
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query = query.transpose([1, 2, 0])
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query = paddle.unsqueeze(query, axis=2)
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res = self.conv1(query)
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res = paddle.squeeze(res, axis=2)
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res = res.transpose([2, 0, 1])
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return res
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def _in_proj_k(self, key):
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key = key.transpose([1, 2, 0])
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key = paddle.unsqueeze(key, axis=2)
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res = self.conv1(key)
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res = paddle.squeeze(res, axis=2)
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res = res.transpose([2, 0, 1])
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return res
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def _in_proj_v(self, value):
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value = value.transpose([1,2,0])#(1, 2, 0)
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value = paddle.unsqueeze(value, axis=2)
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res = self.conv1(value)
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res = paddle.squeeze(res, axis=2)
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res = res.transpose([2, 0, 1])
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return res
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class MultiheadAttentionOptim(nn.Layer):
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r"""Allows the model to jointly attend to information
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