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261 lines
8.6 KiB
261 lines
8.6 KiB
# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import paddle
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from paddle import nn
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__all__ = [
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"Conv1dCell",
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"Conv1dBatchNorm",
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]
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class Conv1dCell(nn.Conv1D):
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"""A subclass of Conv1D layer, which can be used in an autoregressive
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decoder like an RNN cell.
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When used in autoregressive decoding, it performs causal temporal
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convolution incrementally. At each time step, it takes a step input and
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returns a step output.
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Notes
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------
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It is done by caching an internal buffer of length ``receptive_file - 1``.
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when adding a step input, the buffer is shited by one step, the latest
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input is added to be buffer and the oldest step is discarded. And it
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returns a step output. For single step case, convolution is equivalent to a
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linear transformation.
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That it can be used as a cell depends on several restrictions:
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1. stride must be 1;
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2. padding must be a causal padding (recpetive_field - 1, 0).
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Thus, these arguments are removed from the ``__init__`` method of this
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class.
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Parameters
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----------
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in_channels: int
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The feature size of the input.
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out_channels: int
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The feature size of the output.
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kernel_size: int or Tuple[int]
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The size of the kernel.
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dilation: int or Tuple[int]
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The dilation of the convolution, by default 1
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weight_attr: ParamAttr, Initializer, str or bool, optional
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The parameter attribute of the convolution kernel, by default None.
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bias_attr: ParamAttr, Initializer, str or bool, optional
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The parameter attribute of the bias. If ``False``, this layer does not
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have a bias, by default None.
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Examples
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--------
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>>> cell = Conv1dCell(3, 4, kernel_size=5)
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>>> inputs = [paddle.randn([4, 3]) for _ in range(16)]
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>>> outputs = []
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>>> cell.eval()
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>>> cell.start_sequence()
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>>> for xt in inputs:
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>>> outputs.append(cell.add_input(xt))
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>>> len(outputs))
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16
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>>> outputs[0].shape
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[4, 4]
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"""
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def __init__(self,
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in_channels,
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out_channels,
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kernel_size,
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dilation=1,
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weight_attr=None,
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bias_attr=None):
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_dilation = dilation[0] if isinstance(dilation,
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(tuple, list)) else dilation
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_kernel_size = kernel_size[0] if isinstance(kernel_size, (
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tuple, list)) else kernel_size
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self._r = 1 + (_kernel_size - 1) * _dilation
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super(Conv1dCell, self).__init__(
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in_channels,
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out_channels,
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kernel_size,
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padding=(self._r - 1, 0),
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dilation=dilation,
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weight_attr=weight_attr,
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bias_attr=bias_attr,
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data_format="NCL")
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@property
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def receptive_field(self):
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"""The receptive field of the Conv1dCell.
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"""
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return self._r
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def start_sequence(self):
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"""Prepare the layer for a series of incremental forward.
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Warnings
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---------
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This method should be called before a sequence of calls to
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``add_input``.
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Raises
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------
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Exception
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If this method is called when the layer is in training mode.
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"""
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if self.training:
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raise Exception("only use start_sequence in evaluation")
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self._buffer = None
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# NOTE: call self's weight norm hook expliccitly since self.weight
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# is visited directly in this method without calling self.__call__
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# method. If we do not trigger the weight norm hook, the weight
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# may be outdated. e.g. after loading from a saved checkpoint
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# see also: https://github.com/pytorch/pytorch/issues/47588
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for hook in self._forward_pre_hooks.values():
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hook(self, None)
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self._reshaped_weight = paddle.reshape(self.weight,
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(self._out_channels, -1))
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def initialize_buffer(self, x_t):
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"""Initialize the buffer for the step input.
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Parameters
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----------
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x_t : Tensor [shape=(batch_size, in_channels)]
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The step input.
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"""
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batch_size, _ = x_t.shape
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self._buffer = paddle.zeros(
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(batch_size, self._in_channels, self.receptive_field),
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dtype=x_t.dtype)
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def update_buffer(self, x_t):
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"""Shift the buffer by one step.
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Parameters
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----------
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x_t : Tensor [shape=(batch_size, in_channels)]
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The step input.
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"""
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self._buffer = paddle.concat(
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[self._buffer[:, :, 1:], paddle.unsqueeze(x_t, -1)], -1)
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def add_input(self, x_t):
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"""Add step input and compute step output.
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Parameters
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-----------
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x_t : Tensor [shape=(batch_size, in_channels)]
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The step input.
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Returns
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-------
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y_t :Tensor [shape=(batch_size, out_channels)]
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The step output.
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"""
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batch_size = x_t.shape[0]
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if self.receptive_field > 1:
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if self._buffer is None:
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self.initialize_buffer(x_t)
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# update buffer
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self.update_buffer(x_t)
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if self._dilation[0] > 1:
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input = self._buffer[:, :, ::self._dilation[0]]
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else:
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input = self._buffer
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input = paddle.reshape(input, (batch_size, -1))
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else:
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input = x_t
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y_t = paddle.matmul(input, self._reshaped_weight, transpose_y=True)
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y_t = y_t + self.bias
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return y_t
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class Conv1dBatchNorm(nn.Layer):
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"""A Conv1D Layer followed by a BatchNorm1D.
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Parameters
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----------
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in_channels : int
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The feature size of the input.
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out_channels : int
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The feature size of the output.
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kernel_size : int
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The size of the convolution kernel.
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stride : int, optional
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The stride of the convolution, by default 1.
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padding : int, str or Tuple[int], optional
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The padding of the convolution.
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If int, a symmetrical padding is applied before convolution;
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If str, it should be "same" or "valid";
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If Tuple[int], its length should be 2, meaning
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``(pad_before, pad_after)``, by default 0.
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weight_attr : ParamAttr, Initializer, str or bool, optional
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The parameter attribute of the convolution kernel, by default None.
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bias_attr : ParamAttr, Initializer, str or bool, optional
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The parameter attribute of the bias of the convolution, by default
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None.
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data_format : str ["NCL" or "NLC"], optional
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The data layout of the input, by default "NCL"
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momentum : float, optional
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The momentum of the BatchNorm1D layer, by default 0.9
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epsilon : [type], optional
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The epsilon of the BatchNorm1D layer, by default 1e-05
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"""
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def __init__(self,
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in_channels,
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out_channels,
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kernel_size,
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stride=1,
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padding=0,
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weight_attr=None,
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bias_attr=None,
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data_format="NCL",
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momentum=0.9,
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epsilon=1e-05):
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super(Conv1dBatchNorm, self).__init__()
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self.conv = nn.Conv1D(
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in_channels,
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out_channels,
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kernel_size,
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stride,
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padding=padding,
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weight_attr=weight_attr,
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bias_attr=bias_attr,
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data_format=data_format)
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self.bn = nn.BatchNorm1D(
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out_channels,
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momentum=momentum,
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epsilon=epsilon,
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data_format=data_format)
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def forward(self, x):
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"""Forward pass of the Conv1dBatchNorm layer.
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Parameters
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----------
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x : Tensor [shape=(B, C_in, T_in) or (B, T_in, C_in)]
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The input tensor. Its data layout depends on ``data_format``.
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Returns
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-------
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Tensor [shape=(B, C_out, T_out) or (B, T_out, C_out)]
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The output tensor.
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"""
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x = self.conv(x)
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x = self.bn(x)
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return x
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