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import torch
import torch.nn as nn
import torch.nn.functional as F
import torch.fft
import math
# Modified from: https://github.com/thuml/Time-Series-Library
# Modified by Shourya Bose, shbose@ucsc.edu
class Inception_Block_V1(nn.Module):
def __init__(self, in_channels, out_channels, num_kernels=6, init_weight=True):
super(Inception_Block_V1, self).__init__()
self.in_channels = in_channels
self.out_channels = out_channels
self.num_kernels = num_kernels
kernels = []
for i in range(self.num_kernels):
kernels.append(nn.Conv2d(in_channels, out_channels, kernel_size=2 * i + 1, padding=i))
self.kernels = nn.ModuleList(kernels)
if init_weight:
self._initialize_weights()
def _initialize_weights(self):
for m in self.modules():
if isinstance(m, nn.Conv2d):
nn.init.kaiming_normal_(m.weight, mode='fan_out', nonlinearity='relu')
if m.bias is not None:
nn.init.constant_(m.bias, 0)
def forward(self, x):
res_list = []
for i in range(self.num_kernels):
res_list.append(self.kernels[i](x))
res = torch.stack(res_list, dim=-1).mean(-1)
return res
class PositionalEmbedding(nn.Module):
def __init__(self, d_model, max_len=5000):
super(PositionalEmbedding, self).__init__()
# Compute the positional encodings once in log space.
pe = torch.zeros(max_len, d_model).float()
pe.require_grad = False
position = torch.arange(0, max_len).float().unsqueeze(1)
div_term = (torch.arange(0, d_model, 2).float()
* -(math.log(10000.0) / d_model)).exp()
pe[:, 0::2] = torch.sin(position * div_term)
pe[:, 1::2] = torch.cos(position * div_term)
pe = pe.unsqueeze(0)
self.register_buffer('pe', pe)
def forward(self, x):
return self.pe[:, :x.size(1)]
class FixedEmbedding(nn.Module):
def __init__(self, c_in, d_model):
super(FixedEmbedding, self).__init__()
w = torch.zeros(c_in, d_model).float()
w.require_grad = False
position = torch.arange(0, c_in).float().unsqueeze(1)
div_term = (torch.arange(0, d_model, 2).float()
* -(math.log(10000.0) / d_model)).exp()
w[:, 0::2] = torch.sin(position * div_term)
w[:, 1::2] = torch.cos(position * div_term)
self.emb = nn.Embedding(c_in, d_model)
self.emb.weight = nn.Parameter(w, requires_grad=False)
def forward(self, x):
return self.emb(x).detach()
class TemporalEmbedding(nn.Module):
def __init__(self, d_model, embed_type='fixed', freq='h'):
super(TemporalEmbedding, self).__init__()
hour_size = 96
weekday_size = 7
Embed = FixedEmbedding if embed_type == 'fixed' else nn.Embedding
self.hour_embed = Embed(hour_size, d_model)
self.weekday_embed = Embed(weekday_size, d_model)
def forward(self, x):
x = x.long()
hour_x = self.hour_embed(x[:, :, 0])
weekday_x = self.weekday_embed(x[:, :, 1])
return hour_x + weekday_x
class TokenEmbedding(nn.Module):
def __init__(self, c_in, d_model):
super(TokenEmbedding, self).__init__()
padding = 1 if torch.__version__ >= '1.5.0' else 2
self.tokenConv = nn.Conv1d(in_channels=c_in, out_channels=d_model,
kernel_size=3, padding=padding, padding_mode='circular', bias=False)
for m in self.modules():
if isinstance(m, nn.Conv1d):
nn.init.kaiming_normal_(
m.weight, mode='fan_in', nonlinearity='leaky_relu')
def forward(self, x):
x = self.tokenConv(x.permute(0, 2, 1)).transpose(1, 2)
return x
class DataEmbedding(nn.Module):
def __init__(self, c_in, d_model, embed_type='fixed', freq='h', dropout=0.1):
super(DataEmbedding, self).__init__()
self.value_embedding = TokenEmbedding(c_in=c_in, d_model=d_model)
self.position_embedding = PositionalEmbedding(d_model=d_model)
self.temporal_embedding = TemporalEmbedding(d_model=d_model, embed_type=embed_type,
freq=freq)
self.dropout = nn.Dropout(p=dropout)
def forward(self, x, x_mark):
if x_mark is None:
x = self.value_embedding(x) + self.position_embedding(x)
else:
x = self.value_embedding(
x) + self.temporal_embedding(x_mark) + self.position_embedding(x)
return self.dropout(x)
def FFT_for_Period(x, k=2):
# [B, T, C]
xf = torch.fft.rfft(x, dim=1)
# find period by amplitudes
frequency_list = abs(xf).mean(0).mean(-1)
frequency_list[0] = 0
_, top_list = torch.topk(frequency_list, k)
top_list = top_list.detach().cpu().numpy()
period = x.shape[1] // top_list
return period, abs(xf).mean(-1)[:, top_list]
class TimesBlock(nn.Module):
def __init__(self, seq_len, pred_len, top_k, d_model, d_ff, num_kernels):
super(TimesBlock, self).__init__()
self.seq_len = seq_len
self.pred_len = pred_len
self.k = top_k
# parameter-efficient design
self.conv = nn.Sequential(
Inception_Block_V1(d_model, d_ff,
num_kernels=num_kernels),
nn.GELU(),
Inception_Block_V1(d_ff, d_model,
num_kernels=num_kernels)
)
def forward(self, x):
B, T, N = x.size()
period_list, period_weight = FFT_for_Period(x, self.k)
res = []
for i in range(self.k):
period = period_list[i]
# padding
if (self.seq_len + self.pred_len) % period != 0:
length = (
((self.seq_len + self.pred_len) // period) + 1) * period
padding = torch.zeros([x.shape[0], (length - (self.seq_len + self.pred_len)), x.shape[2]]).to(x.device)
out = torch.cat([x, padding], dim=1)
else:
length = (self.seq_len + self.pred_len)
out = x
# reshape
out = out.reshape(B, length // period, period,
N).permute(0, 3, 1, 2).contiguous()
# 2D conv: from 1d Variation to 2d Variation
out = self.conv(out)
# reshape back
out = out.permute(0, 2, 3, 1).reshape(B, -1, N)
res.append(out[:, :(self.seq_len + self.pred_len), :])
res = torch.stack(res, dim=-1)
# adaptive aggregation
period_weight = F.softmax(period_weight, dim=1)
period_weight = period_weight.unsqueeze(
1).unsqueeze(1).repeat(1, T, N, 1)
res = torch.sum(res * period_weight, -1)
# residual connection
res = res + x
return res
class TimesNet(nn.Module):
"""
Paper link: https://openreview.net/pdf?id=ju_Uqw384Oq
"""
def __init__(
self,
enc_in,
dec_in,
c_out,
pred_len,
seq_len,
output_attention = False,
data_idx = [0,3,4,5,6,7],
time_idx = [1,2],
d_model = 16,
d_ff = 64,
e_layers = 2,
top_k = 5,
num_kernels = 2,
dropout = 0.1
):
super(TimesNet, self).__init__()
self.data_idx = data_idx
self.time_idx = time_idx
self.dec_in = dec_in
self.seq_len = seq_len
self.pred_len = pred_len
self.model = nn.ModuleList([TimesBlock(seq_len, pred_len, top_k, d_model, d_ff, num_kernels)
for _ in range(e_layers)])
self.enc_embedding = DataEmbedding(enc_in, d_model, 'fixed', 'h',
dropout)
self.layer = e_layers
self.layer_norm = nn.LayerNorm(d_model)
self.predict_linear = nn.Linear(
self.seq_len, self.pred_len + self.seq_len)
self.projection = nn.Linear(
d_model, c_out, bias=True)
def forecast(self, x_enc, x_mark_enc, x_dec, x_mark_dec):
# Normalization from Non-stationary Transformer
means = x_enc.mean(1, keepdim=True).detach()
x_enc = x_enc - means
stdev = torch.sqrt(
torch.var(x_enc, dim=1, keepdim=True, unbiased=False) + 1e-5)
x_enc /= stdev
# embedding
enc_out = self.enc_embedding(x_enc, x_mark_enc) # [B,T,C]
enc_out = self.predict_linear(enc_out.permute(0, 2, 1)).permute(
0, 2, 1) # align temporal dimension
# TimesNet
for i in range(self.layer):
enc_out = self.layer_norm(self.model[i](enc_out))
# porject back
dec_out = self.projection(enc_out)
# De-Normalization from Non-stationary Transformer
dec_out = dec_out * \
(stdev[:, 0, :].unsqueeze(1).repeat(
1, self.pred_len + self.seq_len, 1))
dec_out = dec_out + \
(means[:, 0, :].unsqueeze(1).repeat(
1, self.pred_len + self.seq_len, 1))
return dec_out
def forward(self, x, fut_time):
x_enc = x[:,:,self.data_idx]
x_mark_enc = x[:,:,self.time_idx]
x_dec = torch.zeros((fut_time.shape[0],fut_time.shape[1],self.dec_in),dtype=fut_time.dtype,device=fut_time.device)
x_mark_dec = fut_time
return self.forecast(x_enc,x_mark_enc,x_dec,x_mark_dec)[:,-1,[0]] |