|
| 1 | +""" |
| 2 | +Date: create on 14/11/2025 |
| 3 | +References: |
| 4 | + paper: (CIKM'2019) AutoInt: Automatic Feature Interaction Learning via Self-Attentive Neural Networks |
| 5 | + url: https://arxiv.org/abs/1810.11921 |
| 6 | +Authors: Yang Zhou, [email protected] |
| 7 | +""" |
| 8 | + |
| 9 | +import torch |
| 10 | +import torch.nn as nn |
| 11 | + |
| 12 | +from ...basic.layers import LR, MLP, EmbeddingLayer, InteractingLayer |
| 13 | + |
| 14 | + |
| 15 | +class AutoInt(torch.nn.Module): |
| 16 | + """AutoInt Model |
| 17 | +
|
| 18 | + Args: |
| 19 | + sparse_features (list): the list of `SparseFeature` Class |
| 20 | + dense_features (list): the list of `DenseFeature` Class |
| 21 | + num_layers (int): number of interacting layers |
| 22 | + num_heads (int): number of attention heads |
| 23 | + dropout (float): dropout rate for attention |
| 24 | + mlp_params (dict): parameters for MLP, keys: {"dims":list, "activation":str, |
| 25 | + "dropout":float, "output_layer":bool"} |
| 26 | + """ |
| 27 | + |
| 28 | + def __init__(self, sparse_features, dense_features, num_layers=3, num_heads=2, dropout=0.0, mlp_params=None): |
| 29 | + super(AutoInt, self).__init__() |
| 30 | + self.sparse_features = sparse_features |
| 31 | + |
| 32 | + self.dense_features = dense_features if dense_features is not None else [] |
| 33 | + embed_dims = [fea.embed_dim for fea in self.sparse_features] |
| 34 | + self.embed_dim = embed_dims[0] |
| 35 | + if len(self.sparse_features) == 0: |
| 36 | + raise ValueError("AutoInt requires at least one sparse feature to determine embed_dim.") |
| 37 | + |
| 38 | + # field nums = sparse + dense |
| 39 | + self.num_sparse = len(self.sparse_features) |
| 40 | + self.num_dense = len(self.dense_features) |
| 41 | + self.num_fields = self.num_sparse + self.num_dense |
| 42 | + |
| 43 | + # total dims = num_fields * embed_dim |
| 44 | + self.dims = self.num_fields * self.embed_dim |
| 45 | + self.num_layers = num_layers |
| 46 | + |
| 47 | + self.sparse_embedding = EmbeddingLayer(self.sparse_features) |
| 48 | + |
| 49 | + # dense feature embedding |
| 50 | + self.dense_embeddings = nn.ModuleDict() |
| 51 | + for fea in self.dense_features: |
| 52 | + self.dense_embeddings[fea.name] = nn.Linear(1, self.embed_dim, bias=False) |
| 53 | + |
| 54 | + self.interacting_layers = torch.nn.ModuleList([InteractingLayer(self.embed_dim, num_heads=num_heads, dropout=dropout, residual=True) for _ in range(num_layers)]) |
| 55 | + |
| 56 | + self.linear = LR(self.dims) |
| 57 | + |
| 58 | + self.attn_linear = nn.Linear(self.dims, 1) |
| 59 | + |
| 60 | + if mlp_params is not None: |
| 61 | + self.use_mlp = True |
| 62 | + self.mlp = MLP(self.dims, **mlp_params) |
| 63 | + else: |
| 64 | + self.use_mlp = False |
| 65 | + |
| 66 | + def forward(self, x): |
| 67 | + # sparse feature embedding: [B, num_sparse, embed_dim] |
| 68 | + sparse_emb = self.sparse_embedding(x, self.sparse_features, squeeze_dim=False) |
| 69 | + |
| 70 | + dense_emb_list = [] |
| 71 | + for fea in self.dense_features: |
| 72 | + v = x[fea.name].float().view(-1, 1, 1) |
| 73 | + dense_emb = self.dense_embeddings[fea.name](v) # [B, 1, embed_dim] |
| 74 | + dense_emb_list.append(dense_emb) |
| 75 | + |
| 76 | + if len(dense_emb_list) > 0: |
| 77 | + dense_emb = torch.cat(dense_emb_list, dim=1) # [B, num_dense, d] |
| 78 | + embed_x = torch.cat([sparse_emb, dense_emb], dim=1) # [B, num_fields, d] |
| 79 | + else: |
| 80 | + embed_x = sparse_emb # [B, num_sparse, d] |
| 81 | + |
| 82 | + embed_x_flatten = embed_x.flatten(start_dim=1) # [B, num_fields * embed_dim] |
| 83 | + |
| 84 | + # Multi-head self-attention layers |
| 85 | + attn_out = embed_x |
| 86 | + for layer in self.interacting_layers: |
| 87 | + attn_out = layer(attn_out) # [B, num_fields, embed_dim] |
| 88 | + |
| 89 | + # Attention linear |
| 90 | + attn_out_flatten = attn_out.flatten(start_dim=1) # [B, num_fields * embed_dim] |
| 91 | + y_attn = self.attn_linear(attn_out_flatten) # [B, 1] |
| 92 | + |
| 93 | + # Linear part |
| 94 | + y_linear = self.linear(embed_x_flatten) # [B, 1] |
| 95 | + |
| 96 | + # Deep MLP |
| 97 | + y = y_attn + y_linear |
| 98 | + if self.use_mlp: |
| 99 | + y_deep = self.mlp(embed_x_flatten) # [B, 1] |
| 100 | + y = y + y_deep |
| 101 | + |
| 102 | + return torch.sigmoid(y.squeeze(1)) |
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