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@ -85,11 +85,11 @@ class PositionalEncoding(nn.Layer, PositionalEncodingInterface):
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reverse (bool, optional): Not used. Defaults to False.
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"""
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nn.Layer.__init__(self)
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self.d_model = d_model
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self.d_model = paddle.to_tensor(d_model)
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self.max_len = max_len
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self.xscale = paddle.to_tensor(math.sqrt(self.d_model))
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self.dropout = nn.Dropout(p=dropout_rate)
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self.base = 10000.0
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self.base = paddle.to_tensor(10000.0)
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self.pe = paddle.zeros([1, self.max_len, self.d_model]) #[B=1,T,D]
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position = paddle.arange(
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@ -97,7 +97,7 @@ class PositionalEncoding(nn.Layer, PositionalEncodingInterface):
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# base^{-2(i-1)/d)}, i \in (1,2...,d/2)
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div_term = paddle.exp(
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-paddle.arange(0, self.d_model, 2, dtype=paddle.float32) *
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(math.log(self.base) / self.d_model))
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(paddle.log(self.base) / self.d_model))
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# [B,T,D]
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self.pe[:, :, 0::2] = paddle.sin(position * div_term)
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@ -188,19 +188,73 @@ class ScaledRotaryRelPositionalEncoding(RelPositionalEncoding):
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scale (int): Interpolation max input length to `scale * max_len` positions.
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"""
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super().__init__(d_model, dropout_rate, max_len, reverse=True)
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self.scale = scale
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self.pscale = paddle.to_tensor(scale)
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self.max_len = max_len * scale
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def sinusoidal_embeddings(self,
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pos: paddle.Tensor,
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dim: paddle.Tensor,
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base=10000) -> paddle.Tensor:
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"""计算pos位置的dim维sinusoidal编码"""
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assert dim % 2 == 0
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# (d/2,)
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indices = paddle.arange(0, dim // 2, dtype=pos.dtype)
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indices = paddle.pow(paddle.cast(base, pos.dtype), -2 * indices / dim)
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# pos (1, T), indices (d/2,) -> (1, T, d/2)
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embeddings = paddle.einsum('...,d->...d', pos, indices)
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# (1, T, d/2, 2)
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embeddings = paddle.stack(
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[paddle.sin(embeddings), paddle.cos(embeddings)], axis=-1)
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# (1, T, d)
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embeddings = paddle.flatten(embeddings, start_axis=-2, stop_axis=-1)
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return embeddings
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def forward(self, x: paddle.Tensor,
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offset: int=0) -> Tuple[paddle.Tensor, paddle.Tensor]:
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"""Compute positional encoding.
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Args:
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x (paddle.Tensor): Input tensor (batch, time, `*`).
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Returns:
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paddle.Tensor: Encoded tensor (batch, time, `*`).
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paddle.Tensor: Positional embedding tensor (1, time, `*`).
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"""
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x = x * self.xscale
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B, T, D = x.shape
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assert D == self.d_model
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# postion interploation
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start = 0
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end = T * self.pscale
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assert end <= self.max_len
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position = paddle.arange(start, end, dtype=x.dtype).unsqueeze(0)
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position *= 1.0 / self.pscale
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pe = self.sinusoidal_embeddings(position, self.d_model, base=self.base)
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pos_emb = pe[:, offset:offset + x.shape[1]]
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return self.dropout(x), self.dropout(pos_emb)
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def position_encoding(self, offset: int, size: int) -> paddle.Tensor:
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""" For getting encoding in a streaming fashion
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Attention!!!!!
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we apply dropout only once at the whole utterance level in a none
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streaming way, but will call this function several times with
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increasing input size in a streaming scenario, so the dropout will
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be applied several times.
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Args:
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offset (int): start offset
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size (int): requried size of position encoding
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Returns:
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paddle.Tensor: Corresponding position encoding, #[1, T, D].
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"""
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# postion interploation
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start = offset
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end = (offset + size) * self.pscale
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assert end <= self.max_len
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position = paddle.arange(
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0, self.max_len, dtype=paddle.float32).unsqueeze(1) #[T, 1]
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# position interpoloation
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position *= 1.0 / self.scale
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start, end, dtype=paddle.get_default_dtype()).unsqueeze(0)
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position *= 1.0 / self.pscale
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# base^{-2(i-1)/d)}, i \in (1,2...,d/2)
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div_term = paddle.exp(
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-paddle.arange(0, self.d_model, 2, dtype=paddle.float32) *
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(math.log(self.base) / self.d_model))
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pe = self.sinusoidal_embeddings(position, self.d_model, base=self.base)
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# [B,T,D]
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self.pe[:, :, 0::2] = paddle.sin(position * div_term)
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self.pe[:, :, 1::2] = paddle.cos(position * div_term)
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return self.dropout(pe)
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