"""NCES modules."""
# From https://github.com/juho-lee/set_transformer
import torch
import torch.nn as nn
import torch.nn.functional as F
import math
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class MAB(nn.Module):
"""MAB module."""
def __init__(self, dim_Q, dim_K, dim_V, num_heads, ln=False):
super(MAB, self).__init__()
self.dim_V = dim_V
self.num_heads = num_heads
self.fc_q = nn.Linear(dim_Q, dim_V)
self.fc_k = nn.Linear(dim_K, dim_V)
self.fc_v = nn.Linear(dim_K, dim_V)
if ln:
self.ln0 = nn.LayerNorm(dim_V)
self.ln1 = nn.LayerNorm(dim_V)
self.fc_o = nn.Linear(dim_V, dim_V)
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def forward(self, Q, K):
Q = self.fc_q(Q)
K, V = self.fc_k(K), self.fc_v(K)
dim_split = self.dim_V // self.num_heads
Q_ = torch.cat(Q.split(dim_split, 2), 0)
K_ = torch.cat(K.split(dim_split, 2), 0)
V_ = torch.cat(V.split(dim_split, 2), 0)
A = torch.softmax(Q_.bmm(K_.transpose(1, 2))/math.sqrt(self.dim_V), 2)
O = torch.cat((Q_ + A.bmm(V_)).split(Q.size(0), 0), 2)
O = O if getattr(self, 'ln0', None) is None else self.ln0(O)
O = O + F.relu(self.fc_o(O))
O = O if getattr(self, 'ln1', None) is None else self.ln1(O)
return O
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class SAB(nn.Module):
"""SAB module."""
def __init__(self, dim_in, dim_out, num_heads, ln=False):
super(SAB, self).__init__()
self.mab = MAB(dim_in, dim_in, dim_out, num_heads, ln=ln)
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def forward(self, X):
return self.mab(X, X)
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class ISAB(nn.Module):
"""ISAB module."""
def __init__(self, dim_in, dim_out, num_heads, num_inds, ln=False):
super(ISAB, self).__init__()
self.I = nn.Parameter(torch.Tensor(1, num_inds, dim_out))
nn.init.xavier_uniform_(self.I)
self.mab0 = MAB(dim_out, dim_in, dim_out, num_heads, ln=ln)
self.mab1 = MAB(dim_in, dim_out, dim_out, num_heads, ln=ln)
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def forward(self, X):
H = self.mab0(self.I.repeat(X.size(0), 1, 1), X)
return self.mab1(X, H)
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class PMA(nn.Module):
"""PMA module."""
def __init__(self, dim, num_heads, num_seeds, ln=False):
super(PMA, self).__init__()
self.S = nn.Parameter(torch.Tensor(1, num_seeds, dim))
nn.init.xavier_uniform_(self.S)
self.mab = MAB(dim, dim, dim, num_heads, ln=ln)
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def forward(self, X):
return self.mab(self.S.repeat(X.size(0), 1, 1), X)