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Upload eva_vit_model.py

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1
+ # --------------------------------------------------------
2
+ # Adapted from https://github.com/microsoft/unilm/tree/master/beit
3
+ # --------------------------------------------------------
4
+ import math
5
+ import os
6
+ from functools import partial
7
+ import torch
8
+ import torch.nn as nn
9
+ import torch.nn.functional as F
10
+ try:
11
+ from timm.models.layers import drop_path, to_2tuple, trunc_normal_
12
+ except:
13
+ from timm.layers import drop_path, to_2tuple, trunc_normal_
14
+
15
+ from .transformer import PatchDropout
16
+ from .rope import VisionRotaryEmbedding, VisionRotaryEmbeddingFast
17
+
18
+ if os.getenv('ENV_TYPE') == 'deepspeed':
19
+ try:
20
+ from deepspeed.runtime.activation_checkpointing.checkpointing import checkpoint
21
+ except:
22
+ from torch.utils.checkpoint import checkpoint
23
+ else:
24
+ from torch.utils.checkpoint import checkpoint
25
+
26
+ try:
27
+ import xformers
28
+ import xformers.ops as xops
29
+ XFORMERS_IS_AVAILBLE = True
30
+ except:
31
+ XFORMERS_IS_AVAILBLE = False
32
+
33
+ class DropPath(nn.Module):
34
+ """Drop paths (Stochastic Depth) per sample (when applied in main path of residual blocks).
35
+ """
36
+ def __init__(self, drop_prob=None):
37
+ super(DropPath, self).__init__()
38
+ self.drop_prob = drop_prob
39
+
40
+ def forward(self, x):
41
+ return drop_path(x, self.drop_prob, self.training)
42
+
43
+ def extra_repr(self) -> str:
44
+ return 'p={}'.format(self.drop_prob)
45
+
46
+
47
+ class Mlp(nn.Module):
48
+ def __init__(
49
+ self,
50
+ in_features,
51
+ hidden_features=None,
52
+ out_features=None,
53
+ act_layer=nn.GELU,
54
+ norm_layer=nn.LayerNorm,
55
+ drop=0.,
56
+ subln=False,
57
+
58
+ ):
59
+ super().__init__()
60
+ out_features = out_features or in_features
61
+ hidden_features = hidden_features or in_features
62
+ self.fc1 = nn.Linear(in_features, hidden_features)
63
+ self.act = act_layer()
64
+
65
+ self.ffn_ln = norm_layer(hidden_features) if subln else nn.Identity()
66
+
67
+ self.fc2 = nn.Linear(hidden_features, out_features)
68
+ self.drop = nn.Dropout(drop)
69
+
70
+ def forward(self, x):
71
+ x = self.fc1(x)
72
+ x = self.act(x)
73
+ # x = self.drop(x)
74
+ # commit this for the orignal BERT implement
75
+ x = self.ffn_ln(x)
76
+
77
+ x = self.fc2(x)
78
+ x = self.drop(x)
79
+ return x
80
+
81
+ class SwiGLU(nn.Module):
82
+ def __init__(self, in_features, hidden_features=None, out_features=None, act_layer=nn.SiLU, drop=0.,
83
+ norm_layer=nn.LayerNorm, subln=False):
84
+ super().__init__()
85
+ out_features = out_features or in_features
86
+ hidden_features = hidden_features or in_features
87
+
88
+ self.w1 = nn.Linear(in_features, hidden_features)
89
+ self.w2 = nn.Linear(in_features, hidden_features)
90
+
91
+ self.act = act_layer()
92
+ self.ffn_ln = norm_layer(hidden_features) if subln else nn.Identity()
93
+ self.w3 = nn.Linear(hidden_features, out_features)
94
+
95
+ self.drop = nn.Dropout(drop)
96
+
97
+ def forward(self, x):
98
+ x1 = self.w1(x)
99
+ x2 = self.w2(x)
100
+ hidden = self.act(x1) * x2
101
+ x = self.ffn_ln(hidden)
102
+ x = self.w3(x)
103
+ x = self.drop(x)
104
+ return x
105
+
106
+ class Attention(nn.Module):
107
+ def __init__(
108
+ self, dim, num_heads=8, qkv_bias=False, qk_scale=None, attn_drop=0.,
109
+ proj_drop=0., window_size=None, attn_head_dim=None, xattn=False, rope=None, subln=False, norm_layer=nn.LayerNorm):
110
+ super().__init__()
111
+ self.num_heads = num_heads
112
+ head_dim = dim // num_heads
113
+ if attn_head_dim is not None:
114
+ head_dim = attn_head_dim
115
+ all_head_dim = head_dim * self.num_heads
116
+ self.scale = qk_scale or head_dim ** -0.5
117
+
118
+ self.subln = subln
119
+ if self.subln:
120
+ self.q_proj = nn.Linear(dim, all_head_dim, bias=False)
121
+ self.k_proj = nn.Linear(dim, all_head_dim, bias=False)
122
+ self.v_proj = nn.Linear(dim, all_head_dim, bias=False)
123
+ else:
124
+ self.qkv = nn.Linear(dim, all_head_dim * 3, bias=False)
125
+
126
+ if qkv_bias:
127
+ self.q_bias = nn.Parameter(torch.zeros(all_head_dim))
128
+ self.v_bias = nn.Parameter(torch.zeros(all_head_dim))
129
+ else:
130
+ self.q_bias = None
131
+ self.v_bias = None
132
+
133
+ if window_size:
134
+ self.window_size = window_size
135
+ self.num_relative_distance = (2 * window_size[0] - 1) * (2 * window_size[1] - 1) + 3
136
+ self.relative_position_bias_table = nn.Parameter(
137
+ torch.zeros(self.num_relative_distance, num_heads)) # 2*Wh-1 * 2*Ww-1, nH
138
+ # cls to token & token 2 cls & cls to cls
139
+
140
+ # get pair-wise relative position index for each token inside the window
141
+ coords_h = torch.arange(window_size[0])
142
+ coords_w = torch.arange(window_size[1])
143
+ coords = torch.stack(torch.meshgrid([coords_h, coords_w])) # 2, Wh, Ww
144
+ coords_flatten = torch.flatten(coords, 1) # 2, Wh*Ww
145
+ relative_coords = coords_flatten[:, :, None] - coords_flatten[:, None, :] # 2, Wh*Ww, Wh*Ww
146
+ relative_coords = relative_coords.permute(1, 2, 0).contiguous() # Wh*Ww, Wh*Ww, 2
147
+ relative_coords[:, :, 0] += window_size[0] - 1 # shift to start from 0
148
+ relative_coords[:, :, 1] += window_size[1] - 1
149
+ relative_coords[:, :, 0] *= 2 * window_size[1] - 1
150
+ relative_position_index = \
151
+ torch.zeros(size=(window_size[0] * window_size[1] + 1, ) * 2, dtype=relative_coords.dtype)
152
+ relative_position_index[1:, 1:] = relative_coords.sum(-1) # Wh*Ww, Wh*Ww
153
+ relative_position_index[0, 0:] = self.num_relative_distance - 3
154
+ relative_position_index[0:, 0] = self.num_relative_distance - 2
155
+ relative_position_index[0, 0] = self.num_relative_distance - 1
156
+
157
+ self.register_buffer("relative_position_index", relative_position_index)
158
+ else:
159
+ self.window_size = None
160
+ self.relative_position_bias_table = None
161
+ self.relative_position_index = None
162
+
163
+ self.attn_drop = nn.Dropout(attn_drop)
164
+ self.inner_attn_ln = norm_layer(all_head_dim) if subln else nn.Identity()
165
+ # self.proj = nn.Linear(all_head_dim, all_head_dim)
166
+ self.proj = nn.Linear(all_head_dim, dim)
167
+ self.proj_drop = nn.Dropout(proj_drop)
168
+ self.xattn = xattn
169
+ self.xattn_drop = attn_drop
170
+
171
+ self.rope = rope
172
+
173
+ def forward(self, x, rel_pos_bias=None, attn_mask=None):
174
+ B, N, C = x.shape
175
+ if self.subln:
176
+ q = F.linear(input=x, weight=self.q_proj.weight, bias=self.q_bias)
177
+ k = F.linear(input=x, weight=self.k_proj.weight, bias=None)
178
+ v = F.linear(input=x, weight=self.v_proj.weight, bias=self.v_bias)
179
+
180
+ q = q.reshape(B, N, self.num_heads, -1).permute(0, 2, 1, 3) # B, num_heads, N, C
181
+ k = k.reshape(B, N, self.num_heads, -1).permute(0, 2, 1, 3)
182
+ v = v.reshape(B, N, self.num_heads, -1).permute(0, 2, 1, 3)
183
+ else:
184
+
185
+ qkv_bias = None
186
+ if self.q_bias is not None:
187
+ qkv_bias = torch.cat((self.q_bias, torch.zeros_like(self.v_bias, requires_grad=False), self.v_bias))
188
+
189
+ qkv = F.linear(input=x, weight=self.qkv.weight, bias=qkv_bias)
190
+ qkv = qkv.reshape(B, N, 3, self.num_heads, -1).permute(2, 0, 3, 1, 4) # 3, B, num_heads, N, C
191
+ q, k, v = qkv[0], qkv[1], qkv[2]
192
+
193
+ if self.rope:
194
+ # slightly fast impl
195
+ q_t = q[:, :, 1:, :]
196
+ ro_q_t = self.rope(q_t)
197
+ q = torch.cat((q[:, :, :1, :], ro_q_t), -2).type_as(v)
198
+
199
+ k_t = k[:, :, 1:, :]
200
+ ro_k_t = self.rope(k_t)
201
+ k = torch.cat((k[:, :, :1, :], ro_k_t), -2).type_as(v)
202
+
203
+ if self.xattn:
204
+ q = q.permute(0, 2, 1, 3) # B, num_heads, N, C -> B, N, num_heads, C
205
+ k = k.permute(0, 2, 1, 3)
206
+ v = v.permute(0, 2, 1, 3)
207
+
208
+ x = xops.memory_efficient_attention(
209
+ q, k, v,
210
+ p=self.xattn_drop,
211
+ scale=self.scale,
212
+ )
213
+ x = x.reshape(B, N, -1)
214
+ x = self.inner_attn_ln(x)
215
+ x = self.proj(x)
216
+ x = self.proj_drop(x)
217
+ else:
218
+ q = q * self.scale
219
+ attn = (q @ k.transpose(-2, -1))
220
+
221
+ if self.relative_position_bias_table is not None:
222
+ relative_position_bias = \
223
+ self.relative_position_bias_table[self.relative_position_index.view(-1)].view(
224
+ self.window_size[0] * self.window_size[1] + 1,
225
+ self.window_size[0] * self.window_size[1] + 1, -1) # Wh*Ww,Wh*Ww,nH
226
+ relative_position_bias = relative_position_bias.permute(2, 0, 1).contiguous() # nH, Wh*Ww, Wh*Ww
227
+ attn = attn + relative_position_bias.unsqueeze(0).type_as(attn)
228
+
229
+ if rel_pos_bias is not None:
230
+ attn = attn + rel_pos_bias.type_as(attn)
231
+
232
+ if attn_mask is not None:
233
+ attn_mask = attn_mask.bool()
234
+ attn = attn.masked_fill(~attn_mask[:, None, None, :], float("-inf"))
235
+
236
+ attn = attn.softmax(dim=-1)
237
+ attn = self.attn_drop(attn)
238
+
239
+ x = (attn @ v).transpose(1, 2).reshape(B, N, -1)
240
+ x = self.inner_attn_ln(x)
241
+ x = self.proj(x)
242
+ x = self.proj_drop(x)
243
+ return x
244
+
245
+
246
+ class Block(nn.Module):
247
+
248
+ def __init__(self, dim, num_heads, mlp_ratio=4., qkv_bias=False, qk_scale=None, drop=0., attn_drop=0.,
249
+ drop_path=0., init_values=None, act_layer=nn.GELU, norm_layer=nn.LayerNorm,
250
+ window_size=None, attn_head_dim=None, xattn=False, rope=None, postnorm=False,
251
+ subln=False, naiveswiglu=False):
252
+ super().__init__()
253
+ self.norm1 = norm_layer(dim)
254
+ self.attn = Attention(
255
+ dim, num_heads=num_heads, qkv_bias=qkv_bias, qk_scale=qk_scale,
256
+ attn_drop=attn_drop, proj_drop=drop, window_size=window_size, attn_head_dim=attn_head_dim,
257
+ xattn=xattn, rope=rope, subln=subln, norm_layer=norm_layer)
258
+ # NOTE: drop path for stochastic depth, we shall see if this is better than dropout here
259
+ self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity()
260
+ self.norm2 = norm_layer(dim)
261
+ mlp_hidden_dim = int(dim * mlp_ratio)
262
+
263
+ if naiveswiglu:
264
+ self.mlp = SwiGLU(
265
+ in_features=dim,
266
+ hidden_features=mlp_hidden_dim,
267
+ subln=subln,
268
+ norm_layer=norm_layer,
269
+ )
270
+ else:
271
+ self.mlp = Mlp(
272
+ in_features=dim,
273
+ hidden_features=mlp_hidden_dim,
274
+ act_layer=act_layer,
275
+ subln=subln,
276
+ drop=drop
277
+ )
278
+
279
+ if init_values is not None and init_values > 0:
280
+ self.gamma_1 = nn.Parameter(init_values * torch.ones((dim)),requires_grad=True)
281
+ self.gamma_2 = nn.Parameter(init_values * torch.ones((dim)),requires_grad=True)
282
+ else:
283
+ self.gamma_1, self.gamma_2 = None, None
284
+
285
+ self.postnorm = postnorm
286
+
287
+ def forward(self, x, rel_pos_bias=None, attn_mask=None):
288
+ if self.gamma_1 is None:
289
+ if self.postnorm:
290
+ x = x + self.drop_path(self.norm1(self.attn(x, rel_pos_bias=rel_pos_bias, attn_mask=attn_mask)))
291
+ x = x + self.drop_path(self.norm2(self.mlp(x)))
292
+ else:
293
+ x = x + self.drop_path(self.attn(self.norm1(x), rel_pos_bias=rel_pos_bias, attn_mask=attn_mask))
294
+ x = x + self.drop_path(self.mlp(self.norm2(x)))
295
+ else:
296
+ if self.postnorm:
297
+ x = x + self.drop_path(self.gamma_1 * self.norm1(self.attn(x, rel_pos_bias=rel_pos_bias, attn_mask=attn_mask)))
298
+ x = x + self.drop_path(self.gamma_2 * self.norm2(self.mlp(x)))
299
+ else:
300
+ x = x + self.drop_path(self.gamma_1 * self.attn(self.norm1(x), rel_pos_bias=rel_pos_bias, attn_mask=attn_mask))
301
+ x = x + self.drop_path(self.gamma_2 * self.mlp(self.norm2(x)))
302
+ return x
303
+
304
+
305
+ class PatchEmbed(nn.Module):
306
+ """ Image to Patch Embedding
307
+ """
308
+ def __init__(self, img_size=224, patch_size=16, in_chans=3, embed_dim=768):
309
+ super().__init__()
310
+ img_size = to_2tuple(img_size)
311
+ patch_size = to_2tuple(patch_size)
312
+ num_patches = (img_size[1] // patch_size[1]) * (img_size[0] // patch_size[0])
313
+ self.patch_shape = (img_size[0] // patch_size[0], img_size[1] // patch_size[1])
314
+ self.img_size = img_size
315
+ self.patch_size = patch_size
316
+ self.num_patches = num_patches
317
+
318
+ self.proj = nn.Conv2d(in_chans, embed_dim, kernel_size=patch_size, stride=patch_size)
319
+
320
+ def forward(self, x, **kwargs):
321
+ B, C, H, W = x.shape
322
+ # FIXME look at relaxing size constraints
323
+ assert H == self.img_size[0] and W == self.img_size[1], \
324
+ f"Input image size ({H}*{W}) doesn't match model ({self.img_size[0]}*{self.img_size[1]})."
325
+ x = self.proj(x).flatten(2).transpose(1, 2)
326
+ return x
327
+
328
+
329
+ class RelativePositionBias(nn.Module):
330
+
331
+ def __init__(self, window_size, num_heads):
332
+ super().__init__()
333
+ self.window_size = window_size
334
+ self.num_relative_distance = (2 * window_size[0] - 1) * (2 * window_size[1] - 1) + 3
335
+ self.relative_position_bias_table = nn.Parameter(
336
+ torch.zeros(self.num_relative_distance, num_heads)) # 2*Wh-1 * 2*Ww-1, nH
337
+ # cls to token & token 2 cls & cls to cls
338
+
339
+ # get pair-wise relative position index for each token inside the window
340
+ coords_h = torch.arange(window_size[0])
341
+ coords_w = torch.arange(window_size[1])
342
+ coords = torch.stack(torch.meshgrid([coords_h, coords_w])) # 2, Wh, Ww
343
+ coords_flatten = torch.flatten(coords, 1) # 2, Wh*Ww
344
+ relative_coords = coords_flatten[:, :, None] - coords_flatten[:, None, :] # 2, Wh*Ww, Wh*Ww
345
+ relative_coords = relative_coords.permute(1, 2, 0).contiguous() # Wh*Ww, Wh*Ww, 2
346
+ relative_coords[:, :, 0] += window_size[0] - 1 # shift to start from 0
347
+ relative_coords[:, :, 1] += window_size[1] - 1
348
+ relative_coords[:, :, 0] *= 2 * window_size[1] - 1
349
+ relative_position_index = \
350
+ torch.zeros(size=(window_size[0] * window_size[1] + 1,) * 2, dtype=relative_coords.dtype)
351
+ relative_position_index[1:, 1:] = relative_coords.sum(-1) # Wh*Ww, Wh*Ww
352
+ relative_position_index[0, 0:] = self.num_relative_distance - 3
353
+ relative_position_index[0:, 0] = self.num_relative_distance - 2
354
+ relative_position_index[0, 0] = self.num_relative_distance - 1
355
+
356
+ self.register_buffer("relative_position_index", relative_position_index)
357
+
358
+ def forward(self):
359
+ relative_position_bias = \
360
+ self.relative_position_bias_table[self.relative_position_index.view(-1)].view(
361
+ self.window_size[0] * self.window_size[1] + 1,
362
+ self.window_size[0] * self.window_size[1] + 1, -1) # Wh*Ww,Wh*Ww,nH
363
+ return relative_position_bias.permute(2, 0, 1).contiguous() # nH, Wh*Ww, Wh*Ww
364
+
365
+
366
+ class EVAVisionTransformer(nn.Module):
367
+ """ Vision Transformer with support for patch or hybrid CNN input stage
368
+ """
369
+ def __init__(self, img_size=224, patch_size=16, in_chans=3, num_classes=1000, embed_dim=768, depth=12,
370
+ num_heads=12, mlp_ratio=4., qkv_bias=False, qk_scale=None, drop_rate=0., attn_drop_rate=0.,
371
+ drop_path_rate=0., norm_layer=nn.LayerNorm, init_values=None, patch_dropout=0.,
372
+ use_abs_pos_emb=True, use_rel_pos_bias=False, use_shared_rel_pos_bias=False, rope=False,
373
+ use_mean_pooling=True, init_scale=0.001, grad_checkpointing=False, xattn=False, postnorm=False,
374
+ pt_hw_seq_len=16, intp_freq=False, naiveswiglu=False, subln=False):
375
+ super().__init__()
376
+
377
+ if not XFORMERS_IS_AVAILBLE:
378
+ xattn = False
379
+
380
+ self.image_size = img_size
381
+ self.num_classes = num_classes
382
+ self.num_features = self.embed_dim = embed_dim # num_features for consistency with other models
383
+
384
+ self.patch_embed = PatchEmbed(
385
+ img_size=img_size, patch_size=patch_size, in_chans=in_chans, embed_dim=embed_dim)
386
+ num_patches = self.patch_embed.num_patches
387
+
388
+ self.cls_token = nn.Parameter(torch.zeros(1, 1, embed_dim))
389
+ # self.mask_token = nn.Parameter(torch.zeros(1, 1, embed_dim))
390
+ if use_abs_pos_emb:
391
+ self.pos_embed = nn.Parameter(torch.zeros(1, num_patches + 1, embed_dim))
392
+ else:
393
+ self.pos_embed = None
394
+ self.pos_drop = nn.Dropout(p=drop_rate)
395
+
396
+ if use_shared_rel_pos_bias:
397
+ self.rel_pos_bias = RelativePositionBias(window_size=self.patch_embed.patch_shape, num_heads=num_heads)
398
+ else:
399
+ self.rel_pos_bias = None
400
+
401
+ if rope:
402
+ half_head_dim = embed_dim // num_heads // 2
403
+ hw_seq_len = img_size // patch_size
404
+ self.rope = VisionRotaryEmbeddingFast(
405
+ dim=half_head_dim,
406
+ pt_seq_len=pt_hw_seq_len,
407
+ ft_seq_len=hw_seq_len if intp_freq else None,
408
+ # patch_dropout=patch_dropout
409
+ )
410
+ else:
411
+ self.rope = None
412
+
413
+ self.naiveswiglu = naiveswiglu
414
+
415
+ dpr = [x.item() for x in torch.linspace(0, drop_path_rate, depth)] # stochastic depth decay rule
416
+ self.use_rel_pos_bias = use_rel_pos_bias
417
+ self.blocks = nn.ModuleList([
418
+ Block(
419
+ dim=embed_dim, num_heads=num_heads, mlp_ratio=mlp_ratio, qkv_bias=qkv_bias, qk_scale=qk_scale,
420
+ drop=drop_rate, attn_drop=attn_drop_rate, drop_path=dpr[i], norm_layer=norm_layer,
421
+ init_values=init_values, window_size=self.patch_embed.patch_shape if use_rel_pos_bias else None,
422
+ xattn=xattn, rope=self.rope, postnorm=postnorm, subln=subln, naiveswiglu=naiveswiglu)
423
+ for i in range(depth)])
424
+ self.norm = nn.Identity() if use_mean_pooling else norm_layer(embed_dim)
425
+ self.fc_norm = norm_layer(embed_dim) if use_mean_pooling else None
426
+ self.head = nn.Linear(embed_dim, num_classes) if num_classes > 0 else nn.Identity()
427
+
428
+ if self.pos_embed is not None:
429
+ trunc_normal_(self.pos_embed, std=.02)
430
+
431
+ trunc_normal_(self.cls_token, std=.02)
432
+ # trunc_normal_(self.mask_token, std=.02)
433
+
434
+ self.apply(self._init_weights)
435
+ self.fix_init_weight()
436
+
437
+ if isinstance(self.head, nn.Linear):
438
+ trunc_normal_(self.head.weight, std=.02)
439
+ self.head.weight.data.mul_(init_scale)
440
+ self.head.bias.data.mul_(init_scale)
441
+
442
+ # setting a patch_dropout of 0. would mean it is disabled and this function would be the identity fn
443
+ self.patch_dropout = PatchDropout(patch_dropout) if patch_dropout > 0. else nn.Identity()
444
+
445
+ self.grad_checkpointing = grad_checkpointing
446
+
447
+ def fix_init_weight(self):
448
+ def rescale(param, layer_id):
449
+ param.div_(math.sqrt(2.0 * layer_id))
450
+
451
+ for layer_id, layer in enumerate(self.blocks):
452
+ rescale(layer.attn.proj.weight.data, layer_id + 1)
453
+ if self.naiveswiglu:
454
+ rescale(layer.mlp.w3.weight.data, layer_id + 1)
455
+ else:
456
+ rescale(layer.mlp.fc2.weight.data, layer_id + 1)
457
+
458
+ def get_cast_dtype(self) -> torch.dtype:
459
+ return self.blocks[0].mlp.fc2.weight.dtype
460
+
461
+ def _init_weights(self, m):
462
+ if isinstance(m, nn.Linear):
463
+ trunc_normal_(m.weight, std=.02)
464
+ if m.bias is not None:
465
+ nn.init.constant_(m.bias, 0)
466
+ elif isinstance(m, nn.LayerNorm):
467
+ nn.init.constant_(m.bias, 0)
468
+ nn.init.constant_(m.weight, 1.0)
469
+
470
+ def get_num_layers(self):
471
+ return len(self.blocks)
472
+
473
+ def lock(self, unlocked_groups=0, freeze_bn_stats=False):
474
+ assert unlocked_groups == 0, 'partial locking not currently supported for this model'
475
+ for param in self.parameters():
476
+ param.requires_grad = False
477
+
478
+ @torch.jit.ignore
479
+ def set_grad_checkpointing(self, enable=True):
480
+ self.grad_checkpointing = enable
481
+
482
+ @torch.jit.ignore
483
+ def no_weight_decay(self):
484
+ return {'pos_embed', 'cls_token'}
485
+
486
+ def get_classifier(self):
487
+ return self.head
488
+
489
+ def reset_classifier(self, num_classes, global_pool=''):
490
+ self.num_classes = num_classes
491
+ self.head = nn.Linear(self.embed_dim, num_classes) if num_classes > 0 else nn.Identity()
492
+
493
+ def forward_features(self, x, return_all_features=False, return_hidden=False, shuffle=False):
494
+
495
+ x = self.patch_embed(x)
496
+ batch_size, seq_len, _ = x.size()
497
+
498
+ if shuffle:
499
+ idx = torch.randperm(x.shape[1]) + 1
500
+ zero = torch.LongTensor([0, ])
501
+ idx = torch.cat([zero, idx])
502
+ pos_embed = self.pos_embed[:, idx]
503
+
504
+ cls_tokens = self.cls_token.expand(batch_size, -1, -1) # stole cls_tokens impl from Phil Wang, thanks
505
+ x = torch.cat((cls_tokens, x), dim=1)
506
+ if shuffle:
507
+ x = x + pos_embed
508
+ elif self.pos_embed is not None:
509
+ x = x + self.pos_embed
510
+ x = self.pos_drop(x)
511
+
512
+ # a patch_dropout of 0. would mean it is disabled and this function would do nothing but return what was passed in
513
+ if os.getenv('RoPE') == '1':
514
+ if self.training and not isinstance(self.patch_dropout, nn.Identity):
515
+ x, patch_indices_keep = self.patch_dropout(x)
516
+ self.rope.forward = partial(self.rope.forward, patch_indices_keep=patch_indices_keep)
517
+ else:
518
+ self.rope.forward = partial(self.rope.forward, patch_indices_keep=None)
519
+ x = self.patch_dropout(x)
520
+ else:
521
+ x = self.patch_dropout(x)
522
+
523
+ rel_pos_bias = self.rel_pos_bias() if self.rel_pos_bias is not None else None
524
+ hidden_states = []
525
+ for idx, blk in enumerate(self.blocks):
526
+ if (0 < idx <= 20) and (idx % 4 == 0) and return_hidden:
527
+ hidden_states.append(x)
528
+ if self.grad_checkpointing:
529
+ x = checkpoint(blk, x, (rel_pos_bias,))
530
+ else:
531
+ x = blk(x, rel_pos_bias=rel_pos_bias)
532
+
533
+ if not return_all_features:
534
+ x = self.norm(x)
535
+ if self.fc_norm is not None:
536
+ return self.fc_norm(x.mean(1)), hidden_states
537
+ else:
538
+ return x[:, 0], hidden_states
539
+ return x
540
+
541
+ def forward(self, x, return_all_features=False, return_hidden=False, shuffle=False):
542
+ if return_all_features:
543
+ return self.forward_features(x, return_all_features, return_hidden, shuffle)
544
+ x, hidden_states = self.forward_features(x, return_all_features, return_hidden, shuffle)
545
+ x = self.head(x)
546
+ if return_hidden:
547
+ return x, hidden_states
548
+ return x