Class: Transformers::Vit::ViTEmbeddings

Inherits:
Torch::NN::Module
  • Object
show all
Defined in:
lib/transformers/models/vit/modeling_vit.rb

Instance Method Summary collapse

Constructor Details

#initialize(config, use_mask_token: false) ⇒ ViTEmbeddings

Returns a new instance of ViTEmbeddings.



18
19
20
21
22
23
24
25
26
27
28
 
# File 'lib/transformers/models/vit/modeling_vit.rb', line 18

def initialize(config, use_mask_token: false)
  super()

  @cls_token = Torch::NN::Parameter.new(Torch.randn(1, 1, config.hidden_size))
  @mask_token = use_mask_token ? Torch::NN::Parameter.new(Torch.zeros(1, 1, config.hidden_size)) : nil
  @patch_embeddings = ViTPatchEmbeddings.new(config)
  num_patches = @patch_embeddings.num_patches
  @position_embeddings = Torch::NN::Parameter.new(Torch.randn(1, num_patches + 1, config.hidden_size))
  @dropout = Torch::NN::Dropout.new(p: config.hidden_dropout_prob)
  @config = config
end

Instance Method Details

#forward(pixel_values, bool_masked_pos: nil, interpolate_pos_encoding: false) ⇒ Object 



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
 
# File 'lib/transformers/models/vit/modeling_vit.rb', line 30

def forward(
  pixel_values,
  bool_masked_pos: nil,
  interpolate_pos_encoding: false
)
  batch_size, _num_channels, height, width = pixel_values.shape
  embeddings = @patch_embeddings.(pixel_values, interpolate_pos_encoding: interpolate_pos_encoding)

  if !bool_masked_pos.nil?
    seq_length = embeddings.shape[1]
    mask_tokens = @mask_token.expand(batch_size, seq_length, -1)
    # replace the masked visual tokens by mask_tokens
    mask = bool_masked_pos.unsqueeze(-1).type_as(mask_tokens)
    embeddings = embeddings * (1.0 - mask) + mask_tokens * mask
  end

  # add the [CLS] token to the embedded patch tokens
  cls_tokens = @cls_token.expand(batch_size, -1, -1)
  embeddings = Torch.cat([cls_tokens, embeddings], dim: 1)

  # add positional encoding to each token
  if interpolate_pos_encoding
    embeddings = embeddings + @interpolate_pos_encoding.(embeddings, height, width)
  else
    embeddings = embeddings + @position_embeddings
  end

  embeddings = @dropout.(embeddings)

  embeddings
end