#!/usr/bin/env python
# Created by "Thieu" at 02:19, 12/05/2025 ----------%
# Email: nguyenthieu2102@gmail.com %
# Github: https://github.com/thieu1995 %
# --------------------------------------------------%
import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F
from sklearn.base import ClassifierMixin, RegressorMixin
from sklearn.metrics import accuracy_score, r2_score
from sklearn.model_selection import train_test_split
from torch.utils.data import TensorDataset, DataLoader
from unilvq.common.early_stopper import EarlyStopper
from unilvq.core.base_model import BaseModel
[docs]class CustomGLVQ(nn.Module):
"""
Custom implementation of the Generalized Learning Vector Quantization (GLVQ) model.
This class defines a neural network-based GLVQ model with trainable prototypes and
a custom loss function for classification tasks.
Attributes
----------
prototypes : torch.nn.Parameter
A tensor containing the trainable prototypes of shape (n_prototypes, input_dim).
prototype_labels : torch.nn.Parameter
A tensor containing the labels of the prototypes, with shape (n_prototypes,).
Methods
-------
forward(x):
Computes the squared Euclidean distance between input samples and prototypes.
glvq_loss(dists, y_true):
Computes the GLVQ loss based on distances and true labels.
"""
def __init__(self, input_dim, n_prototypes, n_classes, seed=None):
super().__init__()
if seed is not None:
torch.manual_seed(seed)
if torch.cuda.is_available():
torch.cuda.manual_seed_all(seed)
self.prototypes = nn.Parameter(torch.randn(n_prototypes, input_dim))
self.prototype_labels = nn.Parameter(torch.randint(0, n_classes, (n_prototypes,)), requires_grad=False)
[docs] def forward(self, x):
"""
Compute the squared Euclidean distance between input samples and prototypes.
"""
return torch.cdist(x, self.prototypes, p=2) ** 2
[docs] def glvq_loss(self, dists, y_true):
"""
Compute the GLVQ loss based on distances and true labels.
"""
batch_size = dists.shape[0]
y_true = y_true.view(-1, 1)
proto_labels = self.prototype_labels.expand(batch_size, -1)
true_mask = (proto_labels == y_true)
false_mask = ~true_mask
d_plus = torch.min(dists.masked_fill(~true_mask, float('inf')), dim=1).values
d_minus = torch.min(dists.masked_fill(~false_mask, float('inf')), dim=1).values
mu = (d_plus - d_minus) / (d_plus + d_minus + 1e-8)
return torch.mean(torch.sigmoid(mu))
[docs]class GlvqClassifier(BaseModel, ClassifierMixin):
"""
Generalized Learning Vector Quantization (GLVQ) Classifier.
This class implements a GLVQ-based classifier using PyTorch. It supports training with early stopping,
validation, and various optimization techniques.
Attributes
----------
n_prototypes_per_class : int
Number of prototypes per class.
epochs : int
Number of training epochs.
batch_size : int
Batch size for training.
optim : str
Name of the optimizer to use (e.g., "Adam", "SGD").
optim_paras : dict
Parameters for the optimizer.
early_stopping : bool
Whether to use early stopping during training.
n_patience : int
Number of epochs to wait for improvement before stopping early.
epsilon : float
Minimum improvement required to reset early stopping patience.
valid_rate : float
Proportion of data to use for validation (between 0 and 1).
seed : int
Random seed for reproducibility.
verbose : bool
Whether to print training progress.
device : str
Device to use for training ("cpu" or "gpu").
Methods
-------
_process_data(X, y):
Prepares data for training and validation.
fit(X, y):
Trains the GLVQ classifier on the given data.
predict(X):
Predicts class labels for the given input data.
score(X, y):
Computes the accuracy of the classifier on the given data.
evaluate(y_true, y_pred, list_metrics=("AS", "RS")):
Evaluates classification performance using specified metrics.
scores(X, y, list_metrics=("AS", "RS")):
Computes classification metrics for the given data.
"""
def __init__(self, n_prototypes_per_class=1, epochs=1000, batch_size=16,
optim="Adam", optim_paras=None,
early_stopping=True, n_patience=10, epsilon=0.001, valid_rate=0.1,
seed=42, verbose=True, device=None):
super().__init__()
self.n_prototypes_per_class = n_prototypes_per_class
self.epochs = epochs
self.batch_size = batch_size
self.optim = optim
self.optim_paras = optim_paras if optim_paras else {}
self.early_stopping = early_stopping
self.n_patience = n_patience
self.epsilon = epsilon
self.valid_rate = valid_rate
self.seed = seed
self.verbose = verbose
if device == 'gpu':
if torch.cuda.is_available():
self.device = 'cuda'
else:
raise ValueError("GPU is not available. Please set device to 'cpu'.")
else:
self.device = "cpu"
self.network, self.optimizer = None, None
self.early_stopper = None
self.valid_mode = False
def _process_data(self, X, y):
X_valid_tensor, y_valid_tensor, X_valid, y_valid = None, None, None, None
# Split data into training and validation sets based on valid_rate
if self.valid_rate is not None:
if 0 < self.valid_rate < 1:
# Activate validation mode if valid_rate is set between 0 and 1
self.valid_mode = True
X, X_valid, y, y_valid = train_test_split(X, y, test_size=self.valid_rate,
random_state=self.seed, shuffle=True, stratify=y)
else:
raise ValueError("Validation rate must be between 0 and 1.")
# Convert data to tensors and set up DataLoader
X_tensor = torch.tensor(X, dtype=torch.float32).to(self.device)
y_tensor = torch.tensor(y, dtype=torch.long).to(self.device)
train_loader = DataLoader(TensorDataset(X_tensor, y_tensor), batch_size=self.batch_size, shuffle=True)
if self.valid_mode:
X_valid_tensor = torch.tensor(X_valid, dtype=torch.float32).to(self.device)
y_valid_tensor = torch.tensor(y_valid, dtype=torch.long).to(self.device)
return train_loader, X_valid_tensor, y_valid_tensor
[docs] def fit(self, X, y):
# Set up data
classes = np.unique(y)
train_loader, X_valid_tensor, y_valid_tensor = self._process_data(X, y)
if self.early_stopping:
# Initialize early stopper if early stopping is enabled
self.early_stopper = EarlyStopper(patience=self.n_patience, epsilon=self.epsilon)
# Define model, optimizer, and loss criterion based on task
self.network = CustomGLVQ(X.shape[1], len(classes) * self.n_prototypes_per_class,
len(classes), seed=self.seed).to(self.device)
self.optimizer = getattr(torch.optim, self.optim)(self.network.parameters(), **self.optim_paras)
proto_labels = []
for c in classes:
proto_labels.extend([c.item()] * self.n_prototypes_per_class)
self.network.prototype_labels[:] = torch.tensor(proto_labels, dtype=torch.long, device=self.device)
# Start training
self.loss_train = []
self.network.train() # Set model to training mode
for epoch in range(self.epochs):
# Initialize total loss for this epoch
total_loss = 0.0
# Training step over batches
for batch_X, batch_y in train_loader:
self.optimizer.zero_grad() # Clear gradients
# Forward pass
output = self.network(batch_X)
loss = self.network.glvq_loss(output, batch_y) # Compute loss
# Backpropagation and optimization
loss.backward()
self.optimizer.step()
total_loss += loss.item() # Accumulate batch loss
# Calculate average training loss for this epoch
avg_loss = total_loss / len(train_loader)
self.loss_train.append(avg_loss)
# Perform validation if validation mode is enabled
if self.valid_mode:
self.network.eval() # Set model to evaluation mode
with torch.no_grad():
val_output = self.network(X_valid_tensor)
val_loss = self.network.glvq_loss(val_output, y_valid_tensor)
# Early stopping based on validation loss
if self.early_stopping and self.early_stopper.early_stop(val_loss):
print(f"Early stopping at epoch {epoch + 1}")
break
if self.verbose:
print(f"Epoch: {epoch + 1}, Train Loss: {avg_loss:.4f}, Validation Loss: {val_loss:.4f}")
else:
# Early stopping based on training loss if no validation is used
if self.early_stopping and self.early_stopper.early_stop(avg_loss):
print(f"Early stopping at epoch {epoch + 1}")
break
if self.verbose:
print(f"Epoch: {epoch + 1}, Train Loss: {avg_loss:.4f}")
# Return to training mode for next epoch
self.network.train()
return self
[docs] def predict(self, X):
"""
Predict the class labels for the input data.
"""
X_tensor = torch.tensor(X, dtype=torch.float32).to(self.device)
self.network.eval()
with torch.no_grad():
output = self.network(X_tensor) # Get model predictions
winner_indices = torch.argmin(output, dim=1) # Find the closest prototype for each sample
preds = self.network.prototype_labels[winner_indices] # Get the corresponding labels
return preds.cpu().numpy()
[docs] def score(self, X, y):
"""Return the accuracy on the given test data and labels."""
return accuracy_score(y, self.predict(X))
[docs] def evaluate(self, y_true, y_pred, list_metrics=("AS", "RS")):
"""Return the list of classification performance metrics of the prediction.
Parameters
----------
y_true : array-like of shape (n_samples,) or (n_samples, n_outputs)
True values for `X`.
y_pred : array-like of shape (n_samples,) or (n_samples, n_outputs)
Predicted values for `X`.
list_metrics : list
You can get classification metrics from Permetrics library: https://permetrics.readthedocs.io/en/latest/pages/classification.html
Returns
-------
results : dict
The results of the list metrics
"""
return self._evaluate_cls(y_true=y_true, y_pred=y_pred, list_metrics=list_metrics)
[docs] def scores(self, X, y, list_metrics=("AS", "RS")):
"""Return the list of classification metrics of the prediction.
Parameters
----------
X : array-like of shape (n_samples, n_features)
Test samples. For some estimators this may be a precomputed kernel matrix or a list of generic objects instead with shape
``(n_samples, n_samples_fitted)``, where ``n_samples_fitted`` is the number of samples used in the fitting for the estimator.
y : array-like of shape (n_samples,) or (n_samples, n_outputs)
True values for `X`.
list_metrics : list, default=("AS", "RS")
You can get classification metrics from Permetrics library: https://permetrics.readthedocs.io/en/latest/pages/classification.html
Returns
-------
results : dict
The results of the list metrics
"""
y_pred = self.predict(X)
return self.evaluate(y, y_pred, list_metrics)
[docs]class GlvqRegressor(BaseModel, RegressorMixin):
"""
Generalized Learning Vector Quantization (GLVQ) Regressor.
This class implements a GLVQ-based regressor using PyTorch. It supports training with early stopping,
validation, and various optimization techniques.
Attributes
----------
n_prototypes : int
Number of prototypes used in the model.
epochs : int
Number of training epochs.
batch_size : int
Batch size for training.
optim : str
Name of the optimizer to use (e.g., "Adam", "SGD").
optim_paras : dict
Parameters for the optimizer.
early_stopping : bool
Whether to use early stopping during training.
n_patience : int
Number of epochs to wait for improvement before stopping early.
epsilon : float
Minimum improvement required to reset early stopping patience.
valid_rate : float
Proportion of data to use for validation (between 0 and 1).
seed : int
Random seed for reproducibility.
verbose : bool
Whether to print training progress.
device : str
Device to use for training ("cpu" or "gpu").
Methods
-------
_process_data(X, y):
Prepares data for training and validation.
fit(X, y):
Trains the GLVQ regressor on the given data.
predict(X):
Predicts target values for the given input data.
score(X, y):
Computes the R^2 score of the regressor on the given data.
evaluate(y_true, y_pred, list_metrics=("MSE", "MAE")):
Evaluates regression performance using specified metrics.
scores(X, y, list_metrics=("MSE", "MAE")):
Computes regression metrics for the given data.
"""
def __init__(self, n_prototypes=10, epochs=1000, batch_size=16,
optim="Adam", optim_paras=None,
early_stopping=True, n_patience=10, epsilon=0.001, valid_rate=0.1,
seed=42, verbose=True, device=None):
super().__init__()
self.n_prototypes = n_prototypes
self.epochs = epochs
self.batch_size = batch_size
self.optim = optim
self.optim_paras = optim_paras if optim_paras else {}
self.early_stopping = early_stopping
self.n_patience = n_patience
self.epsilon = epsilon
self.valid_rate = valid_rate
self.seed = seed
self.verbose = verbose
if device == 'gpu':
if torch.cuda.is_available():
self.device = 'cuda'
else:
raise ValueError("GPU is not available. Please set device to 'cpu'.")
else:
self.device = "cpu"
self.network, self.optimizer = None, None
self.early_stopper = None
self.valid_mode = False
def _process_data(self, X, y):
if y.ndim == 1:
y = y.reshape(-1, 1)
X_valid_tensor, y_valid_tensor, X_valid, y_valid = None, None, None, None
# Split data into training and validation sets based on valid_rate
if self.valid_rate is not None:
if 0 < self.valid_rate < 1:
# Activate validation mode if valid_rate is set between 0 and 1
self.valid_mode = True
X, X_valid, y, y_valid = train_test_split(X, y, test_size=self.valid_rate,
random_state=self.seed, shuffle=True)
else:
raise ValueError("Validation rate must be between 0 and 1.")
# Convert data to tensors and set up DataLoader
X_tensor = torch.tensor(X, dtype=torch.float32).to(self.device)
y_tensor = torch.tensor(y, dtype=torch.float32).to(self.device)
train_loader = DataLoader(TensorDataset(X_tensor, y_tensor), batch_size=self.batch_size, shuffle=True)
if self.valid_mode:
X_valid_tensor = torch.tensor(X_valid, dtype=torch.float32).to(self.device)
y_valid_tensor = torch.tensor(y_valid, dtype=torch.float32).to(self.device)
return train_loader, X_valid_tensor, y_valid_tensor
[docs] def fit(self, X, y):
# Set up data
train_loader, X_valid_tensor, y_valid_tensor = self._process_data(X, y)
if self.early_stopping:
# Initialize early stopper if early stopping is enabled
self.early_stopper = EarlyStopper(patience=self.n_patience, epsilon=self.epsilon)
# Define model, optimizer, and loss criterion based on task
self.network = CustomGLVQ(X.shape[1], self.n_prototypes, 1, seed=self.seed).to(self.device)
self.prototype_targets_ = nn.Parameter(torch.rand(self.n_prototypes, 1, device=self.device))
self.optimizer = getattr(torch.optim, self.optim)(list(self.network.parameters()) + [self.prototype_targets_], **self.optim_paras)
# Start training
self.loss_train = []
self.network.train() # Set model to training mode
for epoch in range(self.epochs):
# Initialize total loss for this epoch
total_loss = 0.0
# Training step over batches
for batch_X, batch_y in train_loader:
self.optimizer.zero_grad() # Clear gradients
# Forward pass
output = self.network(batch_X)
weights = F.softmax(-output, dim=1)
y_pred = weights @ self.prototype_targets_
loss = F.mse_loss(y_pred, batch_y) # Compute loss
# Backpropagation and optimization
loss.backward()
self.optimizer.step()
total_loss += loss.item() # Accumulate batch loss
# Calculate average training loss for this epoch
avg_loss = total_loss / len(train_loader)
self.loss_train.append(avg_loss)
# Perform validation if validation mode is enabled
if self.valid_mode:
self.network.eval() # Set model to evaluation mode
with torch.no_grad():
val_output = self.network(X_valid_tensor)
val_weights = F.softmax(-val_output, dim=1)
val_pred = val_weights @ self.prototype_targets_
val_loss = F.mse_loss(val_pred, y_valid_tensor)
# Early stopping based on validation loss
if self.early_stopping and self.early_stopper.early_stop(val_loss):
print(f"Early stopping at epoch {epoch + 1}")
break
if self.verbose:
print(f"Epoch: {epoch + 1}, Train Loss: {avg_loss:.4f}, Validation Loss: {val_loss:.4f}")
else:
# Early stopping based on training loss if no validation is used
if self.early_stopping and self.early_stopper.early_stop(avg_loss):
print(f"Early stopping at epoch {epoch + 1}")
break
if self.verbose:
print(f"Epoch: {epoch + 1}, Train Loss: {avg_loss:.4f}")
# Return to training mode for next epoch
self.network.train()
return self
[docs] def predict(self, X):
"""
Predict the target values for the input data.
"""
X = torch.tensor(X, dtype=torch.float32).to(self.device)
dists = self.network(X)
weights = F.softmax(-dists, dim=1)
return (weights @ self.prototype_targets_).detach().cpu().numpy()
[docs] def score(self, X, y):
"""
Returns the coefficient of determination R2 of the prediction.
"""
return r2_score(y, self.predict(X))
[docs] def evaluate(self, y_true, y_pred, list_metrics=("MSE", "MAE")):
"""
Returns a list of performance metrics for the predictions.
Parameters
----------
y_true : array-like of shape (n_samples,) or (n_samples, n_outputs)
True values for the input features.
y_pred : array-like of shape (n_samples,) or (n_samples, n_outputs)
Predicted values for the input features.
list_metrics : list, default=("MSE", "MAE")
List of metrics to evaluate (can be from Permetrics library: https://github.com/thieu1995/permetrics).
Returns
-------
results : dict
A dictionary containing the results of the specified metrics.
"""
return self._evaluate_reg(y_true, y_pred, list_metrics) # Call the evaluation method
[docs] def scores(self, X, y, list_metrics=("MSE", "MAE")):
"""
Returns a list of performance metrics for the predictions.
Parameters
----------
X : array-like of shape (n_samples, n_features)
Test samples.
y : array-like of shape (n_samples,) or (n_samples, n_outputs)
True values for the input features.
list_metrics : list, default=("MSE", "MAE")
List of metrics to evaluate (can be from Permetrics library: https://github.com/thieu1995/permetrics).
Returns
-------
results : dict
A dictionary containing the results of the specified metrics.
"""
y_pred = self.predict(X)
return self.evaluate(y, y_pred, list_metrics)