import torch
import torch.nn as nn
import torch.nn.functional as F
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class my_Layernorm(nn.Module):
"""
Special designed layernorm for the seasonal part
"""
def __init__(self, channels):
super(my_Layernorm, self).__init__()
self.layernorm = nn.LayerNorm(channels)
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def forward(self, x):
x_hat = self.layernorm(x)
bias = torch.mean(x_hat, dim=1).unsqueeze(1).repeat(1, x.shape[1], 1)
return x_hat - bias
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class moving_avg(nn.Module):
"""
Moving average block to highlight the trend of time series
"""
def __init__(self, kernel_size, stride):
super(moving_avg, self).__init__()
self.kernel_size = kernel_size
self.avg = nn.AvgPool1d(kernel_size=kernel_size, stride=stride, padding=0)
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def forward(self, x):
# padding on the both ends of time series
front = x[:, 0:1, :].repeat(1, (self.kernel_size - 1) // 2, 1)
end = x[:, -1:, :].repeat(1, (self.kernel_size - 1) // 2, 1)
x = torch.cat([front, x, end], dim=1)
x = self.avg(x.permute(0, 2, 1))
x = x.permute(0, 2, 1)
return x
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class series_decomp(nn.Module):
"""
Series decomposition block
"""
def __init__(self, kernel_size):
super(series_decomp, self).__init__()
self.moving_avg = moving_avg(kernel_size, stride=1)
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def forward(self, x):
moving_mean = self.moving_avg(x)
res = x - moving_mean
return res, moving_mean