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Browse files- positional.py +27 -0
positional.py
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# positional.py
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import torch
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import torch.nn as nn
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from math import log
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class PositionalEncoding(nn.Module):
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def __init__(self, d_model: int, dropout: float = 0.1, max_len: int = 500):
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super().__init__()
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self.dropout = nn.Dropout(p=dropout)
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position = torch.arange(max_len, dtype=torch.float).unsqueeze(1) # (max_len, 1)
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div_term = torch.exp(
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torch.arange(0, d_model, 2, dtype=torch.float) * (-log(10000.0) / d_model)
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) # (d_model/2,)
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pe = torch.zeros(max_len, d_model, dtype=torch.float) # (max_len, d_model)
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pe[:, 0::2] = torch.sin(position * div_term) # (max_len, d_model/2)
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pe[:, 1::2] = torch.cos(position * div_term)
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pe = pe.unsqueeze(0)
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self.register_buffer("pe", pe, persistent=False) # buffer, pas paramètre
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def forward(self, x: torch.Tensor) -> torch.Tensor:
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# x: (B, S, D)
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s = x.size(1)
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x = x + self.pe[:, :s, :] # (1,S,D) broadcast -> (B,S,D)
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return self.dropout(x)
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