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return x
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class FeedForwardBlock(nn.Sequential):
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def __init__(self, emb_size: int, expansion: int = 2, drop_p: float = 0.):
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super().__init__(
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nn.Linear(emb_size, expansion * emb_size),
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nn.GELU(),
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nn.Dropout(drop_p),
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nn.Linear(expansion * emb_size, emb_size),
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)
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class TransformerEncoderBlock(nn.Sequential):
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'''
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We keep the forward expansion as 3, since all the hidden and MLP sizes must be 768 in the transformer encoder
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Ref. 3.6. Transformer Block
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'''
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def __init__(self,
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emb_size: int = 256,
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drop_p: float = 0.,
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forward_expansion: int = 2,
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forward_drop_p: float = 0.,
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** kwargs):
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super().__init__(
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# Zk = MSA(LN(Zk)) + Zk Eq. (7)
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ResidualAdd(nn.Sequential(
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# Layer Normalization (LN)
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nn.LayerNorm(emb_size),
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# Multi Head Self attention (MSA)
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MultiHeadAttention(emb_size, **kwargs),
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nn.Dropout(drop_p)
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)),
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# Zk+1 = MLP(LN(Zk))+ Zk Eq. (8)
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ResidualAdd(nn.Sequential(
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# MLP blocks
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nn.LayerNorm(emb_size),
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FeedForwardBlock(
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emb_size, expansion=forward_expansion, drop_p=forward_drop_p),
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nn.Dropout(drop_p)
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)
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))
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class TransformerEncoder(nn.Sequential):
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'''
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The number 256 is same with projection dimension (attention dimension) d used in the transformer.
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The number of transformer layers is 8. The hidden size and MLP size are 768,
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and the number of heads = 8.
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'''
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def __init__(self, depth: int = 8, **kwargs):
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super().__init__(*[TransformerEncoderBlock(**kwargs) for _ in range(depth)])
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class ClassificationHead(nn.Module):
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'''
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A linear classifier is used to classify the encoded input based on the MLP
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head: ZKcls ∈ R(d). There are two final categorization classes: NC and AD.
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The first token (cls_token) from the sequence is used for classification.
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'''
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def __init__(self, emb_size: int = 256, n_classes: int = 2):
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super().__init__()
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self.linear = nn.Linear(emb_size, n_classes)
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def forward(self, x):
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# As x is of shape [batch_size, num_tokens, emb_size]
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# and the cls_token is the first token in the sequence
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cls_token = x[:, 0]
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return self.linear(cls_token)
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class M3T(nn.Sequential):
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def __init__(self,
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in_channels: int = 1,
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out_channels: int = 32,
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emb_size: int = 256,
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depth: int = 8,
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n_classes: int = 2,
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**kwargs):
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super().__init__(
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CNN3DBlock(in_channels, out_channels),
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MultiPlane_MultiSlice_Extract_Project(out_channels),
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EmbeddingLayer(emb_size=emb_size),
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TransformerEncoder(depth, emb_size=emb_size, **kwargs),
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ClassificationHead(emb_size, n_classes)
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)
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# from torchsummary import summary
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# model = M3T()
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# # Calculate total number of trainable parameters
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# summary(model.to('cuda'), (1, 128, 128, 128))
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# <FILESEP>
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"""This module contains simple helper functions """
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from __future__ import print_function
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import torch
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import numpy as np
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import os
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import imageio
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