wehub-resource-sync
311 lines
11 KiB
Python
311 lines
11 KiB
Python
# Copyright (c) Facebook, Inc. and its affiliates.
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#
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# This source code is licensed under the MIT license found in the
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# LICENSE file in the root directory of this source tree.
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import torch
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import torch.nn as nn
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import torch.nn.functional as F
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from fairseq import utils
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from fairseq.incremental_decoding_utils import with_incremental_state
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from fairseq.modules.fairseq_dropout import FairseqDropout
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from fairseq.modules.unfold import unfold1d
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def LightweightConv(
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input_size,
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kernel_size=1,
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padding_l=None,
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num_heads=1,
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weight_dropout=0.0,
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weight_softmax=False,
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bias=False,
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):
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if torch.cuda.is_available():
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try:
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from fairseq.modules.lightconv_layer import LightconvLayer
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return LightconvLayer(
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input_size,
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kernel_size=kernel_size,
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padding_l=padding_l,
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num_heads=num_heads,
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weight_dropout=weight_dropout,
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weight_softmax=weight_softmax,
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bias=bias,
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)
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except ImportError as e:
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print(e)
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return LightweightConv1dTBC(
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input_size,
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kernel_size=kernel_size,
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padding_l=padding_l,
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num_heads=num_heads,
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weight_dropout=weight_dropout,
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weight_softmax=weight_softmax,
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bias=bias,
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)
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class LightweightConv1d(nn.Module):
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"""Lightweight Convolution assuming the input is BxCxT
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This is just an example that explains LightConv clearer than the TBC version.
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We don't use this module in the model.
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Args:
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input_size: # of channels of the input and output
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kernel_size: convolution channels
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padding: padding
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num_heads: number of heads used. The weight is of shape
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`(num_heads, 1, kernel_size)`
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weight_softmax: normalize the weight with softmax before the convolution
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Shape:
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Input: BxCxT, i.e. (batch_size, input_size, timesteps)
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Output: BxCxT, i.e. (batch_size, input_size, timesteps)
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Attributes:
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weight: the learnable weights of the module of shape
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`(num_heads, 1, kernel_size)`
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bias: the learnable bias of the module of shape `(input_size)`
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"""
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def __init__(
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self,
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input_size,
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kernel_size=1,
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padding=0,
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num_heads=1,
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weight_softmax=False,
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bias=False,
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weight_dropout=0.0,
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):
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super().__init__()
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self.input_size = input_size
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self.kernel_size = kernel_size
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self.num_heads = num_heads
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self.padding = padding
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self.weight_softmax = weight_softmax
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self.weight = nn.Parameter(torch.Tensor(num_heads, 1, kernel_size))
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if bias:
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self.bias = nn.Parameter(torch.Tensor(input_size))
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else:
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self.bias = None
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self.weight_dropout_module = FairseqDropout(
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weight_dropout, module_name=self.__class__.__name__
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)
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self.reset_parameters()
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def reset_parameters(self):
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nn.init.xavier_uniform_(self.weight)
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if self.bias is not None:
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nn.init.constant_(self.bias, 0.0)
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def forward(self, input):
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"""
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input size: B x C x T
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output size: B x C x T
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"""
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B, C, T = input.size()
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H = self.num_heads
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weight = self.weight
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if self.weight_softmax:
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weight = F.softmax(weight, dim=-1)
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weight = self.weight_dropout_module(weight)
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# Merge every C/H entries into the batch dimension (C = self.input_size)
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# B x C x T -> (B * C/H) x H x T
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# One can also expand the weight to C x 1 x K by a factor of C/H
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# and do not reshape the input instead, which is slow though
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input = input.view(-1, H, T)
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output = F.conv1d(input, weight, padding=self.padding, groups=self.num_heads)
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output = output.view(B, C, T)
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if self.bias is not None:
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output = output + self.bias.view(1, -1, 1)
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return output
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@with_incremental_state
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class LightweightConv1dTBC(nn.Module):
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"""Lightweight Convolution assuming the input is TxBxC
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Args:
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input_size: # of channels of the input
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kernel_size: convolution channels
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padding_l: padding to the left when using "same" padding
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num_heads: number of heads used. The weight is of shape (num_heads, 1, kernel_size)
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weight_dropout: the drop rate of the DropConnect to drop the weight
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weight_softmax: normalize the weight with softmax before the convolution
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bias: use bias
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Shape:
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Input: TxBxC, i.e. (timesteps, batch_size, input_size)
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Output: TxBxC, i.e. (timesteps, batch_size, input_size)
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Attributes:
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weight: the learnable weights of the module of shape
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`(num_heads, 1, kernel_size)`
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bias: the learnable bias of the module of shape `(input_size)`
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"""
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def __init__(
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self,
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input_size,
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kernel_size=1,
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padding_l=None,
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num_heads=1,
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weight_dropout=0.0,
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weight_softmax=False,
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bias=False,
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):
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super().__init__()
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self.input_size = input_size
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self.kernel_size = kernel_size
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self.padding_l = padding_l
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self.num_heads = num_heads
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self.weight_dropout_module = FairseqDropout(
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weight_dropout, module_name=self.__class__.__name__
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)
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self.weight_softmax = weight_softmax
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self.weight = nn.Parameter(torch.Tensor(num_heads, 1, kernel_size))
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if bias:
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self.bias = nn.Parameter(torch.Tensor(input_size))
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else:
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self.bias = None
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self.reset_parameters()
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self.onnx_trace = False
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def reset_parameters(self):
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nn.init.xavier_uniform_(self.weight)
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if self.bias is not None:
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nn.init.constant_(self.bias, 0.0)
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def forward(self, x, incremental_state=None, unfold=False):
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"""Assuming the input, x, of the shape T x B x C and producing an output in the shape T x B x C
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args:
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x: Input of shape T x B x C, i.e. (timesteps, batch_size, input_size)
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incremental_state: A dict to keep the state
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unfold: unfold the input or not. If not, we use the matrix trick instead
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"""
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unfold = unfold or (incremental_state is not None)
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if unfold:
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output = self._forward_unfolded(x, incremental_state)
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else:
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output = self._forward_expanded(x, incremental_state)
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if self.bias is not None:
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output = output + self.bias.view(1, 1, -1)
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return output
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def prepare_for_onnx_export_(self):
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self.onnx_trace = True
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def _forward_unfolded(self, x, incremental_state):
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"""The conventional implementation of convolutions.
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Unfolding the input by having a window shifting to the right."""
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T, B, C = x.size()
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K, H = self.kernel_size, self.num_heads
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R = C // H
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assert R * H == C == self.input_size
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weight = self.weight.view(H, K)
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if incremental_state is not None:
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input_buffer = self._get_input_buffer(incremental_state)
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if input_buffer is None:
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input_buffer = x.new()
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x_unfold = torch.cat([input_buffer, x.unsqueeze(3)], dim=3)
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if self.kernel_size > 1:
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self._set_input_buffer(
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incremental_state, x_unfold[:, :, :, -self.kernel_size + 1 :]
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)
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x_unfold = x_unfold.view(T * B * H, R, -1)
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else:
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# unfold the input: T x B x C --> T' x B x C x K
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x_unfold = unfold1d(x, self.kernel_size, self.padding_l, 0)
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x_unfold = x_unfold.view(T * B * H, R, K)
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if self.weight_softmax:
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weight = utils.softmax(weight, dim=1, onnx_trace=self.onnx_trace).type_as(
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weight
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)
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if incremental_state is not None:
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weight = weight[:, -x_unfold.size(2) :]
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K = weight.size(1)
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weight = (
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weight.view(1, H, K).expand(T * B, H, K).contiguous().view(T * B * H, K, 1)
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)
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weight = self.weight_dropout_module(weight)
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output = torch.bmm(x_unfold, weight) # T*B*H x R x 1
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output = output.view(T, B, C)
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return output
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def _forward_expanded(self, x, incremental_state):
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"""Turn the convolution filters into band matrices and do matrix multiplication.
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This is faster when the sequence is short, but less memory efficient.
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This is not used in the decoder during inference.
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"""
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T, B, C = x.size()
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K, H = self.kernel_size, self.num_heads
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R = C // H
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assert R * H == C == self.input_size
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weight = self.weight.view(H, K)
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if self.weight_softmax:
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weight = utils.softmax(weight, dim=1, onnx_trace=self.onnx_trace).type_as(
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weight
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)
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weight = weight.view(1, H, K).expand(T * B, H, K).contiguous()
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weight = weight.view(T, B * H, K).transpose(0, 1)
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x = x.view(T, B * H, R).transpose(0, 1)
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P = self.padding_l
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if K > T and P == K - 1:
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weight = weight.narrow(2, K - T, T)
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K, P = T, T - 1
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# turn the convolution filters into band matrices
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weight_expanded = weight.new_zeros(B * H, T, T + K - 1, requires_grad=False)
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weight_expanded.as_strided((B * H, T, K), (T * (T + K - 1), T + K, 1)).copy_(
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weight
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)
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weight_expanded = weight_expanded.narrow(2, P, T)
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weight_expanded = self.weight_dropout_module(weight_expanded)
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output = torch.bmm(weight_expanded, x)
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output = output.transpose(0, 1).contiguous().view(T, B, C)
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return output
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def reorder_incremental_state(self, incremental_state, new_order):
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input_buffer = self._get_input_buffer(incremental_state)
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if input_buffer is not None:
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input_buffer = input_buffer.index_select(1, new_order)
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self._set_input_buffer(incremental_state, input_buffer)
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def _get_input_buffer(self, incremental_state):
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return utils.get_incremental_state(self, incremental_state, "input_buffer")
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def _set_input_buffer(self, incremental_state, new_buffer):
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return utils.set_incremental_state(
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self, incremental_state, "input_buffer", new_buffer
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)
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def extra_repr(self):
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s = "{}, kernel_size={}, padding_l={}, num_heads={}, weight_softmax={}, bias={}".format(
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self.input_size,
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self.kernel_size,
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self.padding_l,
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self.num_heads,
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self.weight_softmax,
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self.bias is not None,
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)
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if self.weight_dropout_module.p > 0.0:
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s += ", weight_dropout={}".format(self.weight_dropout_module.p)
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return s
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