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import torch |
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import torch.nn as nn |
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import torch.nn.functional as F |
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from timm.models.layers import DropPath |
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class FeatureResizer(nn.Module): |
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""" |
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This class takes as input a set of embeddings of dimension C1 and outputs a set of |
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embedding of dimension C2, after a linear transformation, dropout and normalization (LN). |
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""" |
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def __init__(self, input_feat_size, output_feat_size, dropout, do_ln=True): |
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super().__init__() |
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self.do_ln = do_ln |
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self.fc = nn.Linear(input_feat_size, output_feat_size, bias=True) |
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self.layer_norm = nn.LayerNorm(output_feat_size, eps=1e-12) |
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self.dropout = nn.Dropout(dropout) |
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def forward(self, encoder_features): |
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x = self.fc(encoder_features) |
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if self.do_ln: |
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x = self.layer_norm(x) |
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output = self.dropout(x) |
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return output |
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def l1norm(X, dim, eps=1e-8): |
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"""L1-normalize columns of X""" |
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norm = torch.abs(X).sum(dim=dim, keepdim=True) + eps |
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X = torch.div(X, norm) |
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return X |
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def l2norm(X, dim, eps=1e-8): |
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"""L2-normalize columns of X""" |
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norm = torch.pow(X, 2).sum(dim=dim, keepdim=True).sqrt() + eps |
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X = torch.div(X, norm) |
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return X |
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def func_attention(query, context, smooth=1, raw_feature_norm="softmax", eps=1e-8): |
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""" |
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query: (n_context, queryL, d) |
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context: (n_context, sourceL, d) |
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""" |
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batch_size_q, queryL = query.size(0), query.size(1) |
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batch_size, sourceL = context.size(0), context.size(1) |
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queryT = torch.transpose(query, 1, 2) |
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attn = torch.bmm(context, queryT) |
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if raw_feature_norm == "softmax": |
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attn = attn.view(batch_size * sourceL, queryL) |
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attn = nn.Softmax()(attn) |
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attn = attn.view(batch_size, sourceL, queryL) |
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elif raw_feature_norm == "l2norm": |
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attn = l2norm(attn, 2) |
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elif raw_feature_norm == "clipped_l2norm": |
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attn = nn.LeakyReLU(0.1)(attn) |
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attn = l2norm(attn, 2) |
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else: |
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raise ValueError("unknown first norm type:", raw_feature_norm) |
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attn = torch.transpose(attn, 1, 2).contiguous() |
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attn = attn.view(batch_size * queryL, sourceL) |
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attn = nn.Softmax()(attn * smooth) |
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attn = attn.view(batch_size, queryL, sourceL) |
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attnT = torch.transpose(attn, 1, 2).contiguous() |
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contextT = torch.transpose(context, 1, 2) |
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weightedContext = torch.bmm(contextT, attnT) |
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weightedContext = torch.transpose(weightedContext, 1, 2) |
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return weightedContext, attnT |
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class BiMultiHeadAttention(nn.Module): |
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def __init__(self, v_dim, l_dim, embed_dim, num_heads, dropout=0.1, cfg=None): |
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super(BiMultiHeadAttention, 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.head_dim = embed_dim // num_heads |
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self.v_dim = v_dim |
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self.l_dim = l_dim |
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assert ( |
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self.head_dim * self.num_heads == self.embed_dim |
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), f"embed_dim must be divisible by num_heads (got `embed_dim`: {self.embed_dim} and `num_heads`: {self.num_heads})." |
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self.scale = self.head_dim ** (-0.5) |
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self.dropout = dropout |
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self.v_proj = nn.Linear(self.v_dim, self.embed_dim) |
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self.l_proj = nn.Linear(self.l_dim, self.embed_dim) |
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self.values_v_proj = nn.Linear(self.v_dim, self.embed_dim) |
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self.values_l_proj = nn.Linear(self.l_dim, self.embed_dim) |
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self.out_v_proj = nn.Linear(self.embed_dim, self.v_dim) |
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self.out_l_proj = nn.Linear(self.embed_dim, self.l_dim) |
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self.stable_softmax_2d = True |
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self.clamp_min_for_underflow = True |
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self.clamp_max_for_overflow = True |
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self._reset_parameters() |
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def _shape(self, tensor: torch.Tensor, seq_len: int, bsz: int): |
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return tensor.view(bsz, seq_len, self.num_heads, self.head_dim).transpose(1, 2).contiguous() |
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def _reset_parameters(self): |
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nn.init.xavier_uniform_(self.v_proj.weight) |
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self.v_proj.bias.data.fill_(0) |
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nn.init.xavier_uniform_(self.l_proj.weight) |
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self.l_proj.bias.data.fill_(0) |
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nn.init.xavier_uniform_(self.values_v_proj.weight) |
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self.values_v_proj.bias.data.fill_(0) |
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nn.init.xavier_uniform_(self.values_l_proj.weight) |
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self.values_l_proj.bias.data.fill_(0) |
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nn.init.xavier_uniform_(self.out_v_proj.weight) |
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self.out_v_proj.bias.data.fill_(0) |
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nn.init.xavier_uniform_(self.out_l_proj.weight) |
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self.out_l_proj.bias.data.fill_(0) |
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def forward(self, v, l, attention_mask_v=None, attention_mask_l=None): |
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"""_summary_ |
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Args: |
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v (_type_): bs, n_img, dim |
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l (_type_): bs, n_text, dim |
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attention_mask_v (_type_, optional): _description_. bs, n_img |
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attention_mask_l (_type_, optional): _description_. bs, n_text |
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Returns: |
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_type_: _description_ |
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""" |
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bsz, tgt_len, _ = v.size() |
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query_states = self.v_proj(v) * self.scale |
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key_states = self._shape(self.l_proj(l), -1, bsz) |
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value_v_states = self._shape(self.values_v_proj(v), -1, bsz) |
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value_l_states = self._shape(self.values_l_proj(l), -1, bsz) |
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proj_shape = (bsz * self.num_heads, -1, self.head_dim) |
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query_states = self._shape(query_states, tgt_len, bsz).view(*proj_shape) |
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key_states = key_states.view(*proj_shape) |
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value_v_states = value_v_states.view(*proj_shape) |
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value_l_states = value_l_states.view(*proj_shape) |
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src_len = key_states.size(1) |
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attn_weights = torch.bmm(query_states, key_states.transpose(1, 2)) |
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if attn_weights.size() != (bsz * self.num_heads, tgt_len, src_len): |
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raise ValueError( |
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f"Attention weights should be of size {(bsz * self.num_heads, tgt_len, src_len)}, but is {attn_weights.size()}" |
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) |
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if self.stable_softmax_2d: |
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attn_weights = attn_weights - attn_weights.max() |
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if self.clamp_min_for_underflow: |
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attn_weights = torch.clamp( |
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attn_weights, min=-50000 |
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) |
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if self.clamp_max_for_overflow: |
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attn_weights = torch.clamp( |
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attn_weights, max=50000 |
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) |
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attn_weights_T = attn_weights.transpose(1, 2) |
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attn_weights_l = attn_weights_T - torch.max(attn_weights_T, dim=-1, keepdim=True)[0] |
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if self.clamp_min_for_underflow: |
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attn_weights_l = torch.clamp( |
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attn_weights_l, min=-50000 |
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) |
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if self.clamp_max_for_overflow: |
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attn_weights_l = torch.clamp( |
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attn_weights_l, max=50000 |
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) |
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if attention_mask_v is not None: |
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attention_mask_v = ( |
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attention_mask_v[:, None, None, :].repeat(1, self.num_heads, 1, 1).flatten(0, 1) |
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) |
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attn_weights_l.masked_fill_(attention_mask_v, float("-inf")) |
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attn_weights_l = attn_weights_l.softmax(dim=-1) |
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if attention_mask_l is not None: |
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attention_mask_l = ( |
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attention_mask_l[:, None, None, :].repeat(1, self.num_heads, 1, 1).flatten(0, 1) |
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) |
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attn_weights.masked_fill_(attention_mask_l, float("-inf")) |
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attn_weights_v = attn_weights.softmax(dim=-1) |
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attn_probs_v = F.dropout(attn_weights_v, p=self.dropout, training=self.training) |
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attn_probs_l = F.dropout(attn_weights_l, p=self.dropout, training=self.training) |
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attn_output_v = torch.bmm(attn_probs_v, value_l_states) |
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attn_output_l = torch.bmm(attn_probs_l, value_v_states) |
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if attn_output_v.size() != (bsz * self.num_heads, tgt_len, self.head_dim): |
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raise ValueError( |
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f"`attn_output_v` should be of size {(bsz, self.num_heads, tgt_len, self.head_dim)}, but is {attn_output_v.size()}" |
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) |
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if attn_output_l.size() != (bsz * self.num_heads, src_len, self.head_dim): |
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raise ValueError( |
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f"`attn_output_l` should be of size {(bsz, self.num_heads, src_len, self.head_dim)}, but is {attn_output_l.size()}" |
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) |
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attn_output_v = attn_output_v.view(bsz, self.num_heads, tgt_len, self.head_dim) |
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attn_output_v = attn_output_v.transpose(1, 2) |
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attn_output_v = attn_output_v.reshape(bsz, tgt_len, self.embed_dim) |
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attn_output_l = attn_output_l.view(bsz, self.num_heads, src_len, self.head_dim) |
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attn_output_l = attn_output_l.transpose(1, 2) |
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attn_output_l = attn_output_l.reshape(bsz, src_len, self.embed_dim) |
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attn_output_v = self.out_v_proj(attn_output_v) |
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attn_output_l = self.out_l_proj(attn_output_l) |
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return attn_output_v, attn_output_l |
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class BiAttentionBlock(nn.Module): |
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def __init__( |
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self, |
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v_dim, |
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l_dim, |
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embed_dim, |
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num_heads, |
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dropout=0.1, |
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drop_path=0.0, |
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init_values=1e-4, |
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cfg=None, |
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): |
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""" |
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Inputs: |
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embed_dim - Dimensionality of input and attention feature vectors |
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hidden_dim - Dimensionality of hidden layer in feed-forward network |
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(usually 2-4x larger than embed_dim) |
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num_heads - Number of heads to use in the Multi-Head Attention block |
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dropout - Amount of dropout to apply in the feed-forward network |
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""" |
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super(BiAttentionBlock, self).__init__() |
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self.layer_norm_v = nn.LayerNorm(v_dim) |
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self.layer_norm_l = nn.LayerNorm(l_dim) |
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self.attn = BiMultiHeadAttention( |
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v_dim=v_dim, l_dim=l_dim, embed_dim=embed_dim, num_heads=num_heads, dropout=dropout |
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) |
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self.drop_path = DropPath(drop_path) if drop_path > 0.0 else nn.Identity() |
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self.gamma_v = nn.Parameter(init_values * torch.ones((v_dim)), requires_grad=True) |
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self.gamma_l = nn.Parameter(init_values * torch.ones((l_dim)), requires_grad=True) |
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def forward(self, v, l, attention_mask_v=None, attention_mask_l=None): |
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v = self.layer_norm_v(v) |
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l = self.layer_norm_l(l) |
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delta_v, delta_l = self.attn( |
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v, l, attention_mask_v=attention_mask_v, attention_mask_l=attention_mask_l |
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) |
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v = v + self.drop_path(self.gamma_v * delta_v) |
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l = l + self.drop_path(self.gamma_l * delta_l) |
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return v, l |
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