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tab_network.py
507 lines (435 loc) · 18.7 KB
/
tab_network.py
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import torch
from torch.nn import Linear, BatchNorm1d, ReLU
import numpy as np
from pytorch_tabnet import sparsemax
def initialize_non_glu(module, input_dim, output_dim):
gain_value = np.sqrt((input_dim+output_dim)/np.sqrt(4*input_dim))
torch.nn.init.xavier_normal_(module.weight, gain=gain_value)
# torch.nn.init.zeros_(module.bias)
return
def initialize_glu(module, input_dim, output_dim):
gain_value = np.sqrt((input_dim+output_dim)/np.sqrt(input_dim))
torch.nn.init.xavier_normal_(module.weight, gain=gain_value)
# torch.nn.init.zeros_(module.bias)
return
class GBN(torch.nn.Module):
"""
Ghost Batch Normalization
https://arxiv.org/abs/1705.08741
"""
def __init__(self, input_dim, virtual_batch_size=128, momentum=0.01):
super(GBN, self).__init__()
self.input_dim = input_dim
self.virtual_batch_size = virtual_batch_size
self.bn = BatchNorm1d(self.input_dim, momentum=momentum)
def forward(self, x):
chunks = x.chunk(int(np.ceil(x.shape[0] / self.virtual_batch_size)), 0)
res = [self.bn(x_) for x_ in chunks]
return torch.cat(res, dim=0)
class TabNetNoEmbeddings(torch.nn.Module):
def __init__(self, input_dim, output_dim,
n_d=8, n_a=8,
n_steps=3, gamma=1.3,
n_independent=2, n_shared=2, epsilon=1e-15,
virtual_batch_size=128, momentum=0.02,
mask_type="sparsemax"):
"""
Defines main part of the TabNet network without the embedding layers.
Parameters
----------
- input_dim : int
Number of features
- output_dim : int
Dimension of network output
examples : one for regression, 2 for binary classification etc...
- n_d : int
Dimension of the prediction layer (usually between 4 and 64)
- n_a : int
Dimension of the attention layer (usually between 4 and 64)
- n_steps: int
Number of sucessive steps in the newtork (usually betwenn 3 and 10)
- gamma : float
Float above 1, scaling factor for attention updates (usually betwenn 1.0 to 2.0)
- momentum : float
Float value between 0 and 1 which will be used for momentum in all batch norm
- n_independent : int
Number of independent GLU layer in each GLU block (default 2)
- n_shared : int
Number of independent GLU layer in each GLU block (default 2)
- epsilon: float
Avoid log(0), this should be kept very low
- mask_type: str
Either "sparsemax" or "entmax" : this is the masking function to use
"""
super(TabNetNoEmbeddings, self).__init__()
self.input_dim = input_dim
self.output_dim = output_dim
self.n_d = n_d
self.n_a = n_a
self.n_steps = n_steps
self.gamma = gamma
self.epsilon = epsilon
self.n_independent = n_independent
self.n_shared = n_shared
self.virtual_batch_size = virtual_batch_size
self.mask_type = mask_type
self.initial_bn = BatchNorm1d(self.input_dim, momentum=0.01)
if self.n_shared > 0:
shared_feat_transform = torch.nn.ModuleList()
for i in range(self.n_shared):
if i == 0:
shared_feat_transform.append(Linear(self.input_dim,
2*(n_d + n_a),
bias=False))
else:
shared_feat_transform.append(Linear(n_d + n_a, 2*(n_d + n_a), bias=False))
else:
shared_feat_transform = None
self.initial_splitter = FeatTransformer(self.input_dim, n_d+n_a, shared_feat_transform,
n_glu_independent=self.n_independent,
virtual_batch_size=self.virtual_batch_size,
momentum=momentum)
self.feat_transformers = torch.nn.ModuleList()
self.att_transformers = torch.nn.ModuleList()
for step in range(n_steps):
transformer = FeatTransformer(self.input_dim, n_d+n_a, shared_feat_transform,
n_glu_independent=self.n_independent,
virtual_batch_size=self.virtual_batch_size,
momentum=momentum)
attention = AttentiveTransformer(n_a, self.input_dim,
virtual_batch_size=self.virtual_batch_size,
momentum=momentum,
mask_type=self.mask_type)
self.feat_transformers.append(transformer)
self.att_transformers.append(attention)
self.final_mapping = Linear(n_d, output_dim, bias=False)
initialize_non_glu(self.final_mapping, n_d, output_dim)
def forward(self, x):
res = 0
x = self.initial_bn(x)
prior = torch.ones(x.shape).to(x.device)
M_loss = 0
att = self.initial_splitter(x)[:, self.n_d:]
for step in range(self.n_steps):
M = self.att_transformers[step](prior, att)
M_loss += torch.mean(torch.sum(torch.mul(M, torch.log(M+self.epsilon)),
dim=1))
# update prior
prior = torch.mul(self.gamma - M, prior)
# output
masked_x = torch.mul(M, x)
out = self.feat_transformers[step](masked_x)
d = ReLU()(out[:, :self.n_d])
res = torch.add(res, d)
# update attention
att = out[:, self.n_d:]
M_loss /= self.n_steps
res = self.final_mapping(res)
return res, M_loss
def forward_masks(self, x):
x = self.initial_bn(x)
prior = torch.ones(x.shape).to(x.device)
M_explain = torch.zeros(x.shape).to(x.device)
M_loss = 0
att = self.initial_splitter(x)[:, self.n_d:]
masks = {}
for step in range(self.n_steps):
M = self.att_transformers[step](prior, att)
masks[step] = M
M_loss += torch.mean(torch.sum(torch.mul(M, torch.log(M+self.epsilon)),
dim=1)) / (self.n_steps)
# update prior
prior = torch.mul(self.gamma - M, prior)
# output
masked_x = torch.mul(M, x)
out = self.feat_transformers[step](masked_x)
d = ReLU()(out[:, :self.n_d])
# explain
step_importance = torch.sum(d, dim=1)
M_explain += torch.mul(M, step_importance.unsqueeze(dim=1))
# update attention
att = out[:, self.n_d:]
return M_explain, masks
class TabNet(torch.nn.Module):
def __init__(self, input_dim, output_dim, n_d=8, n_a=8,
n_steps=3, gamma=1.3, cat_idxs=[], cat_dims=[], cat_emb_dim=1,
n_independent=2, n_shared=2, epsilon=1e-15,
virtual_batch_size=128, momentum=0.02, device_name='auto',
mask_type="sparsemax"):
"""
Defines TabNet network
Parameters
----------
- input_dim : int
Initial number of features
- output_dim : int
Dimension of network output
examples : one for regression, 2 for binary classification etc...
- n_d : int
Dimension of the prediction layer (usually between 4 and 64)
- n_a : int
Dimension of the attention layer (usually between 4 and 64)
- n_steps: int
Number of sucessive steps in the newtork (usually betwenn 3 and 10)
- gamma : float
Float above 1, scaling factor for attention updates (usually betwenn 1.0 to 2.0)
- cat_idxs : list of int
Index of each categorical column in the dataset
- cat_dims : list of int
Number of categories in each categorical column
- cat_emb_dim : int or list of int
Size of the embedding of categorical features
if int, all categorical features will have same embedding size
if list of int, every corresponding feature will have specific size
- momentum : float
Float value between 0 and 1 which will be used for momentum in all batch norm
- n_independent : int
Number of independent GLU layer in each GLU block (default 2)
- n_shared : int
Number of independent GLU layer in each GLU block (default 2)
- mask_type: str
Either "sparsemax" or "entmax" : this is the masking function to use
- epsilon: float
Avoid log(0), this should be kept very low
"""
super(TabNet, self).__init__()
self.cat_idxs = cat_idxs or []
self.cat_dims = cat_dims or []
self.cat_emb_dim = cat_emb_dim
self.input_dim = input_dim
self.output_dim = output_dim
self.n_d = n_d
self.n_a = n_a
self.n_steps = n_steps
self.gamma = gamma
self.epsilon = epsilon
self.n_independent = n_independent
self.n_shared = n_shared
self.mask_type = mask_type
if self.n_steps <= 0:
raise ValueError("n_steps should be a positive integer.")
if self.n_independent == 0 and self.n_shared == 0:
raise ValueError("n_shared and n_independant can't be both zero.")
self.virtual_batch_size = virtual_batch_size
self.embedder = EmbeddingGenerator(input_dim, cat_dims, cat_idxs, cat_emb_dim)
self.post_embed_dim = self.embedder.post_embed_dim
self.tabnet = TabNetNoEmbeddings(self.post_embed_dim, output_dim, n_d, n_a, n_steps,
gamma, n_independent, n_shared, epsilon,
virtual_batch_size, momentum, mask_type)
# Defining device
if device_name == 'auto':
if torch.cuda.is_available():
device_name = 'cuda'
else:
device_name = 'cpu'
self.device = torch.device(device_name)
self.to(self.device)
def forward(self, x):
x = self.embedder(x)
return self.tabnet(x)
def forward_masks(self, x):
x = self.embedder(x)
return self.tabnet.forward_masks(x)
class AttentiveTransformer(torch.nn.Module):
def __init__(self, input_dim, output_dim,
virtual_batch_size=128,
momentum=0.02,
mask_type="sparsemax"):
"""
Initialize an attention transformer.
Parameters
----------
- input_dim : int
Input size
- output_dim : int
Outpu_size
- momentum : float
Float value between 0 and 1 which will be used for momentum in batch norm
- mask_type: str
Either "sparsemax" or "entmax" : this is the masking function to use
"""
super(AttentiveTransformer, self).__init__()
self.fc = Linear(input_dim, output_dim, bias=False)
initialize_non_glu(self.fc, input_dim, output_dim)
self.bn = GBN(output_dim, virtual_batch_size=virtual_batch_size,
momentum=momentum)
if mask_type == "sparsemax":
# Sparsemax
self.selector = sparsemax.Sparsemax(dim=-1)
elif mask_type == "entmax":
# Entmax
self.selector = sparsemax.Entmax15(dim=-1)
else:
raise NotImplementedError("Please choose either sparsemax" +
"or entmax as masktype")
def forward(self, priors, processed_feat):
x = self.fc(processed_feat)
x = self.bn(x)
x = torch.mul(x, priors)
x = self.selector(x)
return x
class FeatTransformer(torch.nn.Module):
def __init__(self, input_dim, output_dim, shared_layers, n_glu_independent,
virtual_batch_size=128, momentum=0.02):
super(FeatTransformer, self).__init__()
"""
Initialize a feature transformer.
Parameters
----------
- input_dim : int
Input size
- output_dim : int
Outpu_size
- n_glu_independant
- shared_blocks : torch.nn.ModuleList
The shared block that should be common to every step
- momentum : float
Float value between 0 and 1 which will be used for momentum in batch norm
"""
params = {
'n_glu': n_glu_independent,
'virtual_batch_size': virtual_batch_size,
'momentum': momentum
}
if shared_layers is None:
# no shared layers
self.shared = torch.nn.Identity()
is_first = True
else:
self.shared = GLU_Block(input_dim, output_dim,
first=True,
shared_layers=shared_layers,
n_glu=len(shared_layers),
virtual_batch_size=virtual_batch_size,
momentum=momentum)
is_first = False
if n_glu_independent == 0:
# no independent layers
self.specifics = torch.nn.Identity()
else:
spec_input_dim = input_dim if is_first else output_dim
self.specifics = GLU_Block(spec_input_dim, output_dim,
first=is_first,
**params)
def forward(self, x):
x = self.shared(x)
x = self.specifics(x)
return x
class GLU_Block(torch.nn.Module):
"""
Independant GLU block, specific to each step
"""
def __init__(self, input_dim, output_dim, n_glu=2, first=False, shared_layers=None,
virtual_batch_size=128, momentum=0.02):
super(GLU_Block, self).__init__()
self.first = first
self.shared_layers = shared_layers
self.n_glu = n_glu
self.glu_layers = torch.nn.ModuleList()
params = {
'virtual_batch_size': virtual_batch_size,
'momentum': momentum
}
fc = shared_layers[0] if shared_layers else None
self.glu_layers.append(GLU_Layer(input_dim, output_dim,
fc=fc,
**params))
for glu_id in range(1, self.n_glu):
fc = shared_layers[glu_id] if shared_layers else None
self.glu_layers.append(GLU_Layer(output_dim, output_dim,
fc=fc,
**params))
def forward(self, x):
scale = torch.sqrt(torch.FloatTensor([0.5]).to(x.device))
if self.first: # the first layer of the block has no scale multiplication
x = self.glu_layers[0](x)
layers_left = range(1, self.n_glu)
else:
layers_left = range(self.n_glu)
for glu_id in layers_left:
x = torch.add(x, self.glu_layers[glu_id](x))
x = x*scale
return x
class GLU_Layer(torch.nn.Module):
def __init__(self, input_dim, output_dim, fc=None,
virtual_batch_size=128, momentum=0.02):
super(GLU_Layer, self).__init__()
self.output_dim = output_dim
if fc:
self.fc = fc
else:
self.fc = Linear(input_dim, 2*output_dim, bias=False)
initialize_glu(self.fc, input_dim, 2*output_dim)
self.bn = GBN(2*output_dim, virtual_batch_size=virtual_batch_size,
momentum=momentum)
def forward(self, x):
x = self.fc(x)
x = self.bn(x)
out = torch.mul(x[:, :self.output_dim], torch.sigmoid(x[:, self.output_dim:]))
return out
class EmbeddingGenerator(torch.nn.Module):
"""
Classical embeddings generator
"""
def __init__(self, input_dim, cat_dims, cat_idxs, cat_emb_dim):
""" This is an embedding module for an entier set of features
Parameters
----------
input_dim : int
Number of features coming as input (number of columns)
cat_dims : list of int
Number of modalities for each categorial features
If the list is empty, no embeddings will be done
cat_idxs : list of int
Positional index for each categorical features in inputs
cat_emb_dim : int or list of int
Embedding dimension for each categorical features
If int, the same embdeding dimension will be used for all categorical features
"""
super(EmbeddingGenerator, self).__init__()
if cat_dims == [] or cat_idxs == []:
self.skip_embedding = True
self.post_embed_dim = input_dim
return
self.skip_embedding = False
if isinstance(cat_emb_dim, int):
self.cat_emb_dims = [cat_emb_dim]*len(cat_idxs)
else:
self.cat_emb_dims = cat_emb_dim
# check that all embeddings are provided
if len(self.cat_emb_dims) != len(cat_dims):
msg = """ cat_emb_dim and cat_dims must be lists of same length, got {len(self.cat_emb_dims)}
and {len(cat_dims)}"""
raise ValueError(msg)
self.post_embed_dim = int(input_dim + np.sum(self.cat_emb_dims) - len(self.cat_emb_dims))
self.embeddings = torch.nn.ModuleList()
# Sort dims by cat_idx
sorted_idxs = np.argsort(cat_idxs)
cat_dims = [cat_dims[i] for i in sorted_idxs]
self.cat_emb_dims = [self.cat_emb_dims[i] for i in sorted_idxs]
for cat_dim, emb_dim in zip(cat_dims, self.cat_emb_dims):
self.embeddings.append(torch.nn.Embedding(cat_dim, emb_dim))
# record continuous indices
self.continuous_idx = torch.ones(input_dim, dtype=torch.bool)
self.continuous_idx[cat_idxs] = 0
def forward(self, x):
"""
Apply embdeddings to inputs
Inputs should be (batch_size, input_dim)
Outputs will be of size (batch_size, self.post_embed_dim)
"""
if self.skip_embedding:
# no embeddings required
return x
cols = []
cat_feat_counter = 0
for feat_init_idx, is_continuous in enumerate(self.continuous_idx):
# Enumerate through continuous idx boolean mask to apply embeddings
if is_continuous:
cols.append(x[:, feat_init_idx].float().view(-1, 1))
else:
cols.append(self.embeddings[cat_feat_counter](x[:, feat_init_idx].long()))
cat_feat_counter += 1
# concat
post_embeddings = torch.cat(cols, dim=1)
return post_embeddings