222 lines
8.0 KiB
Python
222 lines
8.0 KiB
Python
from typing import Tuple, List
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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 __init__(self, head_count: int, embed_count: int):
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super().__init__(head_count, embed_count)
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token_indices = torch.arange(256)
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if torch.cuda.is_available(): token_indices = token_indices.cuda()
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self.token_indices = token_indices
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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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token_index: LongTensor
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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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attn_mask = self.token_indices < token_index + 1
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attn_mask = attn_mask[None][[0] * decoder_state.shape[0]]
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attention_state[:, token_index] = torch.cat([keys, values])
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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, attn_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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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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decoder_state, attention_state = self.self_attn.forward(
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decoder_state,
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attention_state,
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token_index
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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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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.embed_count = embed_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.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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attention_mask: BoolTensor,
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encoder_state: FloatTensor,
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attention_state: FloatTensor,
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prev_tokens: LongTensor,
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token_index: LongTensor
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) -> Tuple[LongTensor, FloatTensor]:
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image_count = encoder_state.shape[0] // 2
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token_index_batched = token_index[[0] * image_count * 2]
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prev_tokens = prev_tokens[list(range(image_count)) * 2]
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decoder_state = self.embed_tokens.forward(prev_tokens)
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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 = (
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logits[:image_count, -1] * (1 - a) +
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logits[image_count:, -1] * a
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)
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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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image_count: int,
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text_tokens: LongTensor,
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encoder_state: FloatTensor
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) -> LongTensor:
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expanded_indices = [0] * image_count + [1] * image_count
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text_tokens = text_tokens[expanded_indices]
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encoder_state = encoder_state[expanded_indices]
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attention_mask = text_tokens.not_equal(1)
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attention_state_shape = (
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self.layer_count,
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image_count * 4,
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self.image_token_count,
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self.embed_count
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)
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attention_state = torch.zeros(attention_state_shape)
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if torch.cuda.is_available(): attention_state = attention_state.cuda()
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image_tokens = self.start_token[[0] * image_count]
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image_tokens_sequence: List[LongTensor] = []
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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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attention_mask = attention_mask,
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encoder_state = encoder_state,
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attention_state = attention_state,
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prev_tokens = image_tokens,
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token_index = self.token_indices[[i]]
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)
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image_tokens = torch.multinomial(probs, 1)[:, 0]
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image_tokens_sequence += [image_tokens]
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return torch.stack(image_tokens_sequence).T |