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219 lines
7.8 KiB
219 lines
7.8 KiB
from typing import List, Tuple |
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import torch |
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from torch import LongTensor, nn, FloatTensor, BoolTensor |
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torch.set_grad_enabled(False) |
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from .dalle_bart_encoder import GLU, AttentionBase |
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class DecoderCrossAttention(AttentionBase): |
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def forward( |
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self, |
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decoder_state: FloatTensor, |
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encoder_state: FloatTensor, |
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attention_mask: BoolTensor |
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) -> FloatTensor: |
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keys = self.k_proj.forward(encoder_state) |
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values = self.v_proj.forward(encoder_state) |
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queries = self.q_proj.forward(decoder_state) |
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return super().forward(keys, values, queries, attention_mask) |
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class DecoderSelfAttention(AttentionBase): |
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def forward( |
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self, |
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decoder_state: FloatTensor, |
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attention_state: FloatTensor, |
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attention_mask: BoolTensor, |
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token_mask: BoolTensor |
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) -> Tuple[FloatTensor, FloatTensor]: |
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keys = self.k_proj.forward(decoder_state) |
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values = self.v_proj.forward(decoder_state) |
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queries = self.q_proj.forward(decoder_state) |
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attention_state = torch.where( |
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token_mask[None, :, None], |
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torch.cat([keys, values]), |
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attention_state |
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) |
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batch_count = decoder_state.shape[0] |
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keys = attention_state[:batch_count] |
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values = attention_state[batch_count:] |
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decoder_state = super().forward(keys, values, queries, attention_mask) |
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return decoder_state, attention_state |
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class DecoderLayer(nn.Module): |
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def __init__( |
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self, |
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image_token_count: int, |
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head_count: int, |
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embed_count: int, |
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glu_embed_count: int |
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): |
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super().__init__() |
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self.image_token_count = image_token_count |
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self.pre_self_attn_layer_norm = nn.LayerNorm(embed_count) |
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self.self_attn = DecoderSelfAttention(head_count, embed_count) |
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self.self_attn_layer_norm = nn.LayerNorm(embed_count) |
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self.pre_encoder_attn_layer_norm = nn.LayerNorm(embed_count) |
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self.encoder_attn = DecoderCrossAttention(head_count, embed_count) |
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self.encoder_attn_layer_norm = nn.LayerNorm(embed_count) |
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self.glu = GLU(embed_count, glu_embed_count) |
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self.token_indices = torch.arange(self.image_token_count) |
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if torch.cuda.is_available(): |
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self.token_indices = self.token_indices.cuda() |
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def forward( |
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self, |
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decoder_state: FloatTensor, |
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encoder_state: FloatTensor, |
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attention_state: FloatTensor, |
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attention_mask: BoolTensor, |
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token_index: LongTensor |
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) -> Tuple[FloatTensor, FloatTensor]: |
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# Self Attention |
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residual = decoder_state |
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decoder_state = self.pre_self_attn_layer_norm.forward(decoder_state) |
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self_attn_mask = self.token_indices < token_index + 1 |
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token_mask = self.token_indices == token_index |
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self_attn_mask = torch.stack([self_attn_mask] * decoder_state.shape[0]) |
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decoder_state, attention_state = self.self_attn.forward( |
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decoder_state, |
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attention_state, |
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self_attn_mask, |
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token_mask |
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) |
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decoder_state = self.self_attn_layer_norm.forward(decoder_state) |
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decoder_state = residual + decoder_state |
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# Cross Attention |
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residual = decoder_state |
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decoder_state = self.pre_encoder_attn_layer_norm.forward(decoder_state) |
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decoder_state = self.encoder_attn.forward( |
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decoder_state, |
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encoder_state, |
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attention_mask |
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) |
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decoder_state = self.encoder_attn_layer_norm.forward(decoder_state) |
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decoder_state = residual + decoder_state |
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# Feed forward |
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residual = decoder_state |
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decoder_state = self.glu.forward(decoder_state) |
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decoder_state = residual + decoder_state |
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return decoder_state, attention_state |
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class DalleBartDecoder(nn.Module): |
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def __init__( |
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self, |
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image_vocab_count: int, |
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image_token_count: int, |
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sample_token_count: int, |
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embed_count: int, |
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attention_head_count: int, |
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glu_embed_count: int, |
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layer_count: int, |
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batch_count: int, |
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start_token: int |
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): |
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super().__init__() |
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self.layer_count = layer_count |
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self.sample_token_count = sample_token_count |
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self.condition_factor = 10.0 |
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self.image_token_count = image_token_count |
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self.embed_tokens = nn.Embedding(image_vocab_count + 1, embed_count) |
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self.embed_positions = nn.Embedding(image_token_count, embed_count) |
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self.layers: List[DecoderLayer] = nn.ModuleList([ |
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DecoderLayer( |
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image_token_count, |
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attention_head_count, |
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embed_count, |
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glu_embed_count |
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) |
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for _ in range(layer_count) |
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]) |
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self.layernorm_embedding = nn.LayerNorm(embed_count) |
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self.final_ln = nn.LayerNorm(embed_count) |
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self.lm_head = nn.Linear(embed_count, image_vocab_count + 1, bias=False) |
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self.attention_state_shape = ( |
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layer_count, |
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2 * batch_count, |
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image_token_count, |
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embed_count |
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) |
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self.zero_prob = torch.zeros([1]) |
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self.token_indices = torch.arange(self.sample_token_count) |
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self.start_token = torch.tensor([start_token]).to(torch.long) |
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if torch.cuda.is_available(): |
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self.zero_prob = self.zero_prob.cuda() |
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self.token_indices = self.token_indices.cuda() |
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self.start_token = self.start_token.cuda() |
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def decode_step( |
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self, |
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text_tokens: LongTensor, |
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encoder_state: FloatTensor, |
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attention_state: FloatTensor, |
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prev_token: LongTensor, |
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token_index: LongTensor |
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) -> Tuple[LongTensor, FloatTensor]: |
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attention_mask = text_tokens.not_equal(1) |
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batch_count = encoder_state.shape[0] |
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prev_token_batched = torch.cat([prev_token] * batch_count) |
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token_index_batched = torch.cat([token_index] * batch_count) |
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decoder_state = self.embed_tokens.forward(prev_token_batched) |
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decoder_state += self.embed_positions.forward(token_index_batched) |
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decoder_state = self.layernorm_embedding.forward(decoder_state) |
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decoder_state = decoder_state[:, None] |
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attention_states_new = [] |
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for i in range(self.layer_count): |
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decoder_state, attention_state_layer = self.layers[i].forward( |
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decoder_state, |
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encoder_state, |
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attention_state[i], |
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attention_mask, |
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token_index |
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) |
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attention_states_new.append(attention_state_layer) |
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decoder_state = self.final_ln(decoder_state) |
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logits = self.lm_head(decoder_state) |
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a = self.condition_factor |
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logits: FloatTensor = (1 - a) * logits[0, -1] + a * logits[1, -1] |
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top_logits, _ = logits.topk(50, dim=-1) |
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probs = torch.where( |
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logits < top_logits[-1], |
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self.zero_prob, |
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torch.exp(logits - top_logits[0]) |
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) |
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return probs, torch.stack(attention_states_new) |
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def forward( |
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self, |
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text_tokens: LongTensor, |
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encoder_state: FloatTensor |
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) -> LongTensor: |
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image_tokens: List[LongTensor] = [] |
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attention_state = torch.zeros(self.attention_state_shape) |
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if torch.cuda.is_available(): |
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attention_state = attention_state.cuda() |
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image_token = self.start_token |
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for i in range(self.sample_token_count): |
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probs, attention_state = self.decode_step( |
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text_tokens = text_tokens, |
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encoder_state = encoder_state, |
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attention_state = attention_state, |
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prev_token = image_token, |
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token_index = self.token_indices[[i]] |
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) |
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image_token = torch.multinomial(probs, 1) |
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image_tokens += [image_token] |
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return torch.cat(image_tokens) |