File size: 20,866 Bytes
be639cb
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
import torch
import torch.nn as nn
import numpy as np

# ---------------- Meta Components ----------------
class MetaNet(nn.Module):
    def __init__(self, input_dim, xprime_dim):
        super().__init__()
        self.layer1 = nn.Linear(1, input_dim * xprime_dim)
        self.layer2 = nn.Linear(input_dim * xprime_dim, input_dim * xprime_dim)
        self.input_dim = input_dim
        self.xprime_dim = xprime_dim

    def forward(self, x_feat):  # x_feat: [B, 1]
        B = x_feat.size(0)
        out = torch.tanh(self.layer1(x_feat))            # [B, 32]
        out = torch.tanh(self.layer2(out))               # [B, input_dim * xprime_dim]
        return out.view(B, self.input_dim, self.xprime_dim)  # [B, input_dim, xprime_dim]



class GatingNet(nn.Module):
    def __init__(self, hidden_size, num_experts=3):
        super().__init__()
        self.layer1 = nn.Linear(hidden_size, hidden_size)
        self.layer2 = nn.Linear(hidden_size, num_experts)

    def forward(self, h, epoch=None, top_k=None, warmup_epochs=0):
        logits = self.layer2(torch.tanh(self.layer1(h)))  # [B, num_experts]

        if (epoch is None) or (top_k is None) or (epoch < warmup_epochs):
            return torch.softmax(logits, dim=-1)

        topk_vals, topk_idx = torch.topk(logits, k=top_k, dim=-1)
        mask = torch.zeros_like(logits).scatter(1, topk_idx, 1.0)
        masked_logits = logits.masked_fill(mask == 0, float('-inf'))
        return torch.softmax(masked_logits, dim=-1)


class MetaTransformBlock(nn.Module):
    def __init__(self, xprime_dim, num_experts=3, input_dim=1, hidden_size=64):
        super().__init__()
        self.meta_temp = MetaNet(input_dim, xprime_dim)
        self.meta_work = MetaNet(input_dim, xprime_dim)
        self.meta_season = MetaNet(input_dim, xprime_dim)
        self.gating = GatingNet(hidden_size, num_experts)  # Use hidden_size here
        self.ln = nn.LayerNorm([input_dim, xprime_dim])
        self.theta0 = nn.Parameter(torch.zeros(1, input_dim, xprime_dim))

    def forward(self, h_prev_rnn, x_l, x_t, x_w, x_s, epoch=None, top_k=None, warmup_epochs=0):
        w_temp = self.ln(self.meta_temp(x_t))     # [B, input_dim, xprime_dim]
        w_work = self.ln(self.meta_work(x_w))     # [B, input_dim, xprime_dim]
        w_seas = self.ln(self.meta_season(x_s))   # [B, input_dim, xprime_dim]

        gates = self.gating(h_prev_rnn, epoch=epoch, top_k=top_k, warmup_epochs=warmup_epochs)  # [B, num_experts]
        W_experts = torch.stack([w_temp, w_work, w_seas], dim=1)  # [B, num_experts, input_dim, xprime_dim]
        gates_expanded = gates.view(gates.size(0), gates.size(1), 1, 1)  # [B, num_experts, 1, 1]
        theta_dynamic = (W_experts * gates_expanded).sum(dim=1)  # [B, input_dim, xprime_dim]
        theta = theta_dynamic + self.theta0                      # [B, input_dim, xprime_dim]

        x_prime = torch.bmm(x_l.unsqueeze(1), theta).squeeze(1)  # [B, xprime_dim]
        return x_prime, theta

# ---------------- Encoder ----------------
class Encoder_meta(nn.Module):
    def __init__(self, xprime_dim, hidden_size, num_layers=1, dropout=0.1):
        super().__init__()
        self.hidden_size = hidden_size
        self.num_layers = num_layers
        self.rnn = nn.GRU(xprime_dim, hidden_size, num_layers,
                          batch_first=True,
                          dropout=dropout if num_layers > 1 else 0)

    def forward(self, x_l_seq, x_t_seq, x_w_seq, x_s_seq,
                transform_block, h_init=None, epoch=None, top_k=None, warmup_epochs=0):
        B, T, _ = x_l_seq.shape
        h_rnn = torch.zeros(self.num_layers, B, self.hidden_size, device=x_l_seq.device) if h_init is None else h_init

        for t in range(T):
            h_for_meta = h_rnn[-1]
            x_prime, _ = transform_block(h_for_meta,
                                         x_l_seq[:, t], x_t_seq[:, t],
                                         x_w_seq[:, t], x_s_seq[:, t],
                                         epoch=epoch, top_k=top_k, warmup_epochs=warmup_epochs)
            x_prime = x_prime.unsqueeze(1)
            _, h_rnn = self.rnn(x_prime, h_rnn)

        return h_rnn  # [num_layers, B, hidden_size]


# ---------------- Decoder ----------------
class Decoder_meta(nn.Module):
    def __init__(self, xprime_dim, latent_size, output_len, output_dim=1,
                 num_layers=1, dropout=0.1, hidden_size=None):
        super().__init__()
        self.latent_size = latent_size
        self.output_len = output_len
        self.output_dim = output_dim
        self.num_layers = num_layers

        self.rnn = nn.GRU(xprime_dim, latent_size, num_layers,
                          batch_first=True,
                          dropout=dropout if num_layers > 1 else 0)

        self.head = nn.Linear(latent_size, output_len * output_dim)

        # Layer-wise projection from encoder hidden_size → decoder latent_size
        assert hidden_size is not None, "You must provide hidden_size for projection."
        self.project = nn.ModuleList([
            nn.Linear(hidden_size, latent_size) for _ in range(num_layers)
        ])

    def forward(self, x_l_seq, x_t_seq, x_w_seq, x_s_seq,
                h_init, transform_block,
                epoch=None, top_k=None, warmup_epochs=0):
        B, L, _ = x_l_seq.shape

        # Project each layer of encoder hidden state to latent size
        h_rnn = torch.stack([
            self.project[i](h_init[i]) for i in range(self.num_layers)
        ], dim=0)  # [num_layers, B, latent_size]

        preds = []

        # Step 0
        h_last = h_rnn[-1]  # [B, latent_size]
        pred_0 = self.head(h_last).view(B, self.output_len, self.output_dim)
        preds.append(pred_0.unsqueeze(1))  # [B, 1, output_len, output_dim]

        # Steps 1 to L
        for t in range(L):
            h_for_meta = h_rnn[-1]
            x_prime, _ = transform_block(h_for_meta,
                                         x_l_seq[:, t], x_t_seq[:, t],
                                         x_w_seq[:, t], x_s_seq[:, t],
                                         epoch=epoch, top_k=top_k, warmup_epochs=warmup_epochs)
            x_prime = x_prime.unsqueeze(1)
            out_t, h_rnn = self.rnn(x_prime, h_rnn)
            pred_t = self.head(out_t.squeeze(1)).view(B, self.output_len, self.output_dim)
            preds.append(pred_t.unsqueeze(1))

        preds = torch.cat(preds, dim=1)  # [B, L+1, output_len, output_dim]
        return preds


# ---------------- Full Seq2Seq Model ----------------
class Seq2Seq_meta(nn.Module):
    def __init__(self, xprime_dim, input_dim, hidden_size, latent_size,
                 output_len, output_dim=1, num_layers=1, dropout=0.1, num_experts=3):
        super().__init__()

        self.transform_enc = MetaTransformBlock(
            xprime_dim=xprime_dim,
            num_experts=num_experts,
            input_dim=input_dim,
            hidden_size=hidden_size  # encoder hidden_size
        )

        self.transform_dec = MetaTransformBlock(
            xprime_dim=xprime_dim,
            num_experts=num_experts,
            input_dim=input_dim,
            hidden_size=latent_size  # decoder latent_size
        )

        self.encoder = Encoder_meta(
            xprime_dim=xprime_dim,
            hidden_size=hidden_size,
            num_layers=num_layers,
            dropout=dropout)

        self.decoder = Decoder_meta(
            xprime_dim=xprime_dim,
            latent_size=latent_size,
            output_len=output_len,
            output_dim=output_dim,
            num_layers=num_layers,
            dropout=dropout,
            hidden_size=hidden_size  # for projection from encoder hidden
        )

    def forward(self,
                enc_l, enc_t, enc_w, enc_s,
                dec_l, dec_t, dec_w, dec_s,
                epoch=None, top_k=None, warmup_epochs=0):

        h_enc = self.encoder(enc_l, enc_t, enc_w, enc_s,
                             transform_block=self.transform_enc,
                             epoch=epoch, top_k=top_k, warmup_epochs=warmup_epochs)

        preds = self.decoder(dec_l, dec_t, dec_w, dec_s,
                             h_init=h_enc,
                             transform_block=self.transform_dec,
                             epoch=epoch, top_k=top_k, warmup_epochs=warmup_epochs)
        return preds



# ---------------- Encoder ----------------
class VariationalEncoder_meta(nn.Module):
    def __init__(self, xprime_dim, hidden_size, latent_size, num_layers=1, dropout=0.1):
        super().__init__()
        self.hidden_size = hidden_size
        self.latent_size = latent_size
        self.num_layers = num_layers

        self.rnn = nn.GRU(xprime_dim, hidden_size, num_layers,
                          batch_first=True,
                          dropout=dropout if num_layers > 1 else 0)

        self.mu_layer = nn.Linear(hidden_size, latent_size)
        self.logvar_layer = nn.Linear(hidden_size, latent_size)

    def forward(self, x_l_seq, x_t_seq, x_w_seq, x_s_seq,
                transform_block, h_init=None, epoch=None, top_k=None, warmup_epochs=0):

        B, T, _ = x_l_seq.shape
        h_rnn = torch.zeros(self.num_layers, B, self.hidden_size, device=x_l_seq.device) if h_init is None else h_init

        for t in range(T):
            h_for_meta = h_rnn[-1]
            x_prime, _ = transform_block(h_for_meta,
                                         x_l_seq[:, t], x_t_seq[:, t],
                                         x_w_seq[:, t], x_s_seq[:, t],
                                         epoch=epoch, top_k=top_k, warmup_epochs=warmup_epochs)
            x_prime = x_prime.unsqueeze(1)
            _, h_rnn = self.rnn(x_prime, h_rnn)

        h_last = h_rnn[-1]  # [B, hidden_size]
        mu = self.mu_layer(h_last)
        logvar = self.logvar_layer(h_last)

        return mu, logvar



class VariationalDecoder_meta_predvar(nn.Module):
    def __init__(self, xprime_dim, latent_size, output_len, output_dim=1,
                 num_layers=1, dropout=0.1):
        super().__init__()
        self.latent_size = latent_size
        self.output_len = output_len
        self.output_dim = output_dim
        self.num_layers = num_layers

        self.rnn = nn.GRU(xprime_dim, latent_size, num_layers,
                          batch_first=True,
                          dropout=dropout if num_layers > 1 else 0)

        # Separate heads for mean and log-variance
        self.head_mu = nn.Linear(latent_size, output_len * output_dim)
        self.head_logvar = nn.Linear(latent_size, output_len * output_dim)

    def forward(self, x_l_seq, x_t_seq, x_w_seq, x_s_seq,
                z_latent, transform_block,
                epoch=None, top_k=None, warmup_epochs=0):
        B, L, _ = x_l_seq.shape

        h_rnn = z_latent.unsqueeze(0).repeat(self.num_layers, 1, 1)  # [num_layers, B, latent_size]

        mu_preds = []
        logvar_preds = []

        # Step 0
        h_last = h_rnn[-1]
        mu_0 = self.head_mu(h_last).view(B, self.output_len, self.output_dim)
        logvar_0 = self.head_logvar(h_last).view(B, self.output_len, self.output_dim)
        mu_preds.append(mu_0.unsqueeze(1))           # [B, 1, output_len, output_dim]
        logvar_preds.append(logvar_0.unsqueeze(1))   # same shape

        # Steps 1 to L
        for t in range(L):
            h_for_meta = h_rnn[-1]
            x_prime, _ = transform_block(h_for_meta,
                                         x_l_seq[:, t], x_t_seq[:, t],
                                         x_w_seq[:, t], x_s_seq[:, t],
                                         epoch=epoch, top_k=top_k, warmup_epochs=warmup_epochs)
            x_prime = x_prime.unsqueeze(1)
            out_t, h_rnn = self.rnn(x_prime, h_rnn)

            mu_t = self.head_mu(out_t.squeeze(1)).view(B, self.output_len, self.output_dim)
            logvar_t = self.head_logvar(out_t.squeeze(1)).view(B, self.output_len, self.output_dim)

            mu_preds.append(mu_t.unsqueeze(1))
            logvar_preds.append(logvar_t.unsqueeze(1))

        # Stack across time
        mu_preds = torch.cat(mu_preds, dim=1)         # [B, L+1, output_len, output_dim]
        logvar_preds = torch.cat(logvar_preds, dim=1) # same shape

        return mu_preds, logvar_preds


# ---------------- Full Seq2Seq Model ----------------
class VariationalSeq2Seq_meta(nn.Module):
    def __init__(self, xprime_dim, input_dim, hidden_size, latent_size,
                 output_len, output_dim=1, num_layers=1, dropout=0.1, num_experts=3):
        super().__init__()

        self.transform_enc = MetaTransformBlock(
            xprime_dim=xprime_dim,
            num_experts=num_experts,
            input_dim=input_dim,
            hidden_size=hidden_size  # encoder hidden size
        )

        self.transform_dec = MetaTransformBlock(
            xprime_dim=xprime_dim,
            num_experts=num_experts,
            input_dim=input_dim,
            hidden_size=latent_size  # decoder latent size
        )

        self.encoder = VariationalEncoder_meta(
            xprime_dim=xprime_dim,
            hidden_size=hidden_size,
            latent_size=latent_size,
            num_layers=num_layers,
            dropout=dropout
        )

        # self.decoder = VariationalDecoder_meta_fixvar(
        #     xprime_dim=xprime_dim,
        #     latent_size=latent_size,
        #     output_len=output_len,
        #     output_dim=output_dim,
        #     num_layers=num_layers,
        #     dropout=dropout
        # )

        self.decoder = VariationalDecoder_meta_predvar(
            xprime_dim=xprime_dim,
            latent_size=latent_size,
            output_len=output_len,
            output_dim=output_dim,
            num_layers=num_layers,
            dropout=dropout
        )

    def reparameterize(self, mu, logvar):
        std = torch.exp(0.5 * logvar)
        eps = torch.randn_like(std)
        return mu + eps * std

    def forward(self,
                enc_l, enc_t, enc_w, enc_s,
                dec_l, dec_t, dec_w, dec_s,
                epoch=None, top_k=None, warmup_epochs=0):

        mu, logvar = self.encoder(enc_l, enc_t, enc_w, enc_s,
                                  transform_block=self.transform_enc,
                                  epoch=epoch, top_k=top_k, warmup_epochs=warmup_epochs)

        z = self.reparameterize(mu, logvar)  # [B, latent_size]

        mu_preds, logvar_preds = self.decoder(dec_l, dec_t, dec_w, dec_s,
                             z_latent=z,
                             transform_block=self.transform_dec,
                             epoch=epoch, top_k=top_k, warmup_epochs=warmup_epochs)

        return mu_preds, logvar_preds, mu, logvar






# # ---------------- Decoder v1: fixed variance ----------------
# class VariationalDecoder_meta_fixvar(nn.Module):
#     def __init__(self, xprime_dim, latent_size, output_len, output_dim=1,
#                  num_layers=1, dropout=0.1, fixed_var_value=0.01):
#         super().__init__()
#         self.latent_size = latent_size
#         self.output_len = output_len
#         self.output_dim = output_dim
#         self.num_layers = num_layers
#
#         self.rnn = nn.GRU(xprime_dim, latent_size, num_layers,
#                           batch_first=True,
#                           dropout=dropout if num_layers > 1 else 0)
#
#         self.head = nn.Linear(latent_size, output_len * output_dim)
#
#         # Fixed log-variance (scalar)
#         self.fixed_logvar = torch.tensor(np.log(fixed_var_value), dtype=torch.float32)
#
#     def forward(self, x_l_seq, x_t_seq, x_w_seq, x_s_seq,
#                 z_latent, transform_block,
#                 epoch=None, top_k=None, warmup_epochs=0):
#         B, L, _ = x_l_seq.shape
#
#         h_rnn = z_latent.unsqueeze(0).repeat(self.num_layers, 1, 1)  # [num_layers, B, latent_size]
#
#         mu_preds = []
#
#         # Step 0
#         h_last = h_rnn[-1]
#         mu_0 = self.head(h_last).view(B, self.output_len, self.output_dim)
#         mu_preds.append(mu_0.unsqueeze(1))  # [B, 1, output_len, output_dim]
#
#         # Steps 1 to L
#         for t in range(L):
#             h_for_meta = h_rnn[-1]
#             x_prime, _ = transform_block(h_for_meta,
#                                          x_l_seq[:, t], x_t_seq[:, t],
#                                          x_w_seq[:, t], x_s_seq[:, t],
#                                          epoch=epoch, top_k=top_k, warmup_epochs=warmup_epochs)
#             x_prime = x_prime.unsqueeze(1)
#             out_t, h_rnn = self.rnn(x_prime, h_rnn)
#
#             mu_t = self.head(out_t.squeeze(1)).view(B, self.output_len, self.output_dim)
#             mu_preds.append(mu_t.unsqueeze(1))
#
#         mu_preds = torch.cat(mu_preds, dim=1)  # [B, L+1, output_len, output_dim]
#
#         # Now create logvar_preds: same shape, filled with fixed_logvar
#         logvar_preds = self.fixed_logvar.expand_as(mu_preds).to(mu_preds.device)
#
#         return mu_preds, logvar_preds
#


# ---------------- Decoder v2: predicted variance ----------------


#
# ## LSTM
# import torch, torch.nn as nn
# import torch.nn.functional as F
#
# class LSTM_Baseline(nn.Module):
#     """
#     Simple encoder‑decoder LSTM baseline.
#     • All four modal inputs (load, temp, workday, season) are concatenated along feature dim
#       so the external information is still available, but the model is otherwise “plain”.
#     • The forward signature (extra **kwargs) lets the old training loop pass epoch/top_k/warmup
#       without breaking anything.
#     """
#     def __init__(
#         self,
#         input_dim: int,      # 1  →  only the scalar value of each channel
#         hidden_size: int,    # e.g. 64
#         output_len: int,     # prediction horizon (3)
#         output_dim: int = 1, # scalar prediction
#         num_layers: int = 2,
#         dropout: float = 0.1,
#     ):
#         super().__init__()
#         self.hidden_size  = hidden_size
#         self.output_len   = output_len
#         self.output_dim   = output_dim
#         self.num_layers   = num_layers
#
#         # encoder & decoder
#         self.encoder = nn.LSTM(
#             input_size = input_dim * 4,    # four channels concatenated
#             hidden_size = hidden_size,
#             num_layers = num_layers,
#             batch_first = True,
#             dropout = dropout if num_layers > 1 else 0.0,
#         )
#         self.decoder = nn.LSTM(
#             input_size = input_dim * 4,
#             hidden_size = hidden_size,
#             num_layers = num_layers,
#             batch_first = True,
#             dropout = dropout if num_layers > 1 else 0.0,
#         )
#
#         self.out_layer = nn.Linear(hidden_size, output_dim)
#
#     def forward(
#         self,
#         enc_l, enc_t, enc_w, enc_s,
#         dec_l, dec_t, dec_w, dec_s,
#         *unused, **unused_kw,
#     ):
#         """
#         enc_* : [B, Lenc, 1]      (load / temp / workday / season)
#         dec_* : [B, Ldec, 1]
#         return: [B, Lenc+1, output_len, 1]  (to keep your downstream code intact)
#         """
#         B, Lenc, _ = enc_l.shape
#
#         # 1) ---------- Encode ----------
#         enc_in = torch.cat([enc_l, enc_t, enc_w, enc_s], dim=-1)   # [B, Lenc, 4]
#         _, (h_n, c_n) = self.encoder(enc_in)                       # carry hidden to decoder
#
#         # 2) ---------- Decode ----------
#         Ldec = dec_l.size(1)                                        # usually 1 step (the teacher‑force token)
#         dec_in = torch.cat([dec_l, dec_t, dec_w, dec_s], dim=-1)    # [B, Ldec, 4]
#         dec_out, _ = self.decoder(dec_in, (h_n, c_n))               # [B, Ldec, H]
#         y0 = self.out_layer(dec_out[:, -1])                         # last step → [B, output_dim]
#
#         # 3) ---------- Autoregressive forecast ----------
#         preds = []
#         ht, ct = h_n, c_n
#         xt = dec_in[:, -1]                                          # start token
#         for _ in range(self.output_len):
#             xt = xt.unsqueeze(1)                                    # [B,1,4]
#             out, (ht, ct) = self.decoder(xt, (ht, ct))              # [B,1,H]
#             yt = self.out_layer(out.squeeze(1))                     # [B, output_dim]
#             preds.append(yt)
#             # next decoder input = last prediction repeated over 4 channels
#             xt = torch.cat([yt]*4, dim=-1)
#
#         # 3) ---------- Autoregressive forecast ----------
#         preds = torch.stack(preds, dim=1)  # [B, H, 1]
#
#         # 4) ---------- match original return shape ----------
#         seq_len_y = enc_l.size(1) - self.output_len + 1  # <-- NEW: 168‑>166
#         preds = preds.unsqueeze(1).repeat(1, seq_len_y, 1, 1)
#         return preds  # [B, 166, 3, 1]
#