58 lines
2.4 KiB
Python
58 lines
2.4 KiB
Python
import torch
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import torch.nn as nn
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class VideoClassifierV3_2(nn.Module):
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def __init__(self, embedding_dim=1024, hidden_dim=512, output_dim=3):
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super().__init__()
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self.num_channels = 4
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self.channel_names = ['title', 'description', 'tags', 'author_info']
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# 改进1：带温度系数的通道权重（比原始固定权重更灵活）
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self.channel_weights = nn.Parameter(torch.ones(self.num_channels))
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self.temperature = 1.7 # 可调节的平滑系数
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# 改进2：更稳健的全连接结构
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self.fc = nn.Sequential(
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nn.Linear(embedding_dim * self.num_channels, hidden_dim*2),
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nn.BatchNorm1d(hidden_dim*2),
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nn.Dropout(0.1),
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nn.ReLU(),
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nn.Linear(hidden_dim*2, hidden_dim),
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nn.LayerNorm(hidden_dim),
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nn.Linear(hidden_dim, output_dim)
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)
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# 改进3：输出层初始化
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nn.init.xavier_uniform_(self.fc[-1].weight)
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nn.init.zeros_(self.fc[-1].bias)
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def forward(self, input_texts, sentence_transformer):
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# 合并所有通道文本进行批量编码
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all_texts = [text for channel in self.channel_names for text in input_texts[channel]]
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# 使用SentenceTransformer生成嵌入（保持冻结）
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with torch.no_grad():
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task = "classification"
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embeddings = torch.tensor(
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sentence_transformer.encode(all_texts, task=task),
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device=next(self.parameters()).device
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)
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# 分割嵌入并加权
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split_sizes = [len(input_texts[name]) for name in self.channel_names]
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channel_features = torch.split(embeddings, split_sizes, dim=0)
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channel_features = torch.stack(channel_features, dim=1) # [batch, 4, 1024]
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# 改进4：带温度系数的softmax加权
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weights = torch.softmax(self.channel_weights / self.temperature, dim=0)
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weighted_features = channel_features * weights.unsqueeze(0).unsqueeze(-1)
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# 拼接特征
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combined = weighted_features.view(weighted_features.size(0), -1)
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# 全连接层
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return self.fc(combined)
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def get_channel_weights(self):
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"""获取各通道权重（带温度调节）"""
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return torch.softmax(self.channel_weights / self.temperature, dim=0).detach().cpu().numpy() |