OptiTrainer is an advanced training framework designed to enhance the performance and robustness of deep learning models, with a primary focus on image classification tasks. This framework integrates multiple advanced training strategies, demonstrating significant accuracy improvements (up to 7%) on standard datasets such as CIFAR-10 compared to conventional training approaches.

• Standard Training Pipeline (normal_train.py): A baseline implementation providing a straightforward training and validation workflow for performance comparison.
• Optimized Training Pipeline (train.py): Implements two powerful ensemble strategies:
  • K-Fold Cross Validation with Diversity: Enhances model generalization through stratified data splitting and diverse data augmentation across folds
  • Snapshot Ensemble: Generates multiple model snapshots during a single training run with cosine annealing learning rate scheduling
• Advanced Training Components: Cosine annealing learning rate scheduling, automatic best model checkpointing, and soft-voting ensemble inference
• Customizable Architecture: Flexible design supporting user-defined models and datasets

# Clone OptiTrainer
git clone https://github.com/Jackksonns/OptiTrainer.git
cd OptiTrainer

• CIFAR-10 dataset is used by default and will be automatically downloaded on first run
• For custom datasets, organize data in PyTorch-compatible format and modify the data loading section in train.py and normal_train.py

• Standard training (baseline):

  python normal_train.py

• Optimized training (K-Fold by default):

  python train.py

# K-Fold implementation snippet
def get_stratified_kfold_indices(labels, n_splits=5, random_state=SEED, shuffle=True):
    skf = StratifiedKFold(n_splits=n_splits, shuffle=shuffle, random_state=random_state)
    labels = np.array(labels)
    train_idxs_list, val_idxs_list = [], []
    for tr, vl in skf.split(np.zeros(len(labels)), labels):
        train_idxs_list.append(tr)
        val_idxs_list.append(vl)
    return train_idxs_list, val_idxs_list

• Stratified Splitting: Maintains class distribution across folds using StratifiedKFold from scikit-learn
• Diversity Enhancement: Each fold uses different random seeds and data augmentation strategies
• Per-Fold Optimization: Independent training with automatic best model selection for each fold

• Single training run with periodic model checkpoints (snapshots) at specified intervals
• Leverages cosine annealing learning rate scheduling to encourage diverse model states
• Efficient alternative to traditional cross-validation with reduced computational overhead

# Ensemble prediction implementation
stacked = torch.stack(all_fold_preds, dim=0)  # [k, N, C] (if logits, it's logits)
# Weighted averaging based on validation accuracy
if use_weighted:
    w = np.array(best_acc_list, dtype=float)
    w = w / w.sum()
    w_t = torch.tensor(w, dtype=stacked.dtype).view(-1,1,1)
    final_probs = (stacked * w_t).sum(dim=0)
else:
    final_probs = torch.mean(stacked, dim=0)

• Soft-Voting: Aggregates predictions from multiple models using probability averaging
• Weighted Ensemble: Option to weight models by their validation performance
• Configurable Input: Supports averaging of probabilities or logits

• method: Training strategy ('kfold_diverse' or 'snapshot')
• SEED: Random seed for reproducibility
• num_epochs: Number of training epochs per fold or for snapshot training
• init_lr: Initial learning rate
• n_splits: Number of folds for cross-validation

• use_weighted: Whether to use validation accuracy for weighted ensemble
• ensemble_from: Input type for ensemble ('probs' or 'logits')
• snap_interval: Interval between snapshots (for snapshot method)

• On CIFAR-10 dataset, OptiTrainer demonstrates up to 7% higher accuracy (72% vs. 65%) compared to standard training pipelines with the same model architecture and training duration(with same init lr and epochs)

• #mormal training process  --result
  step: 153000, train loss: 0.7846522927284241
  epoch 195 | test loss: 1.1244, test acc: 0.6547
  
  #OptiTrainer training process  --result
  Ensemble test acc: 0.7213
  Per-fold test accs: [0.6993, 0.6945, 0.6892, 0.6976, 0.695]
  Pairwise disagreement:
   [[0.     0.1981 0.2252 0.1869 0.1623]
   [0.1981 0.     0.2003 0.2069 0.2106]
   [0.2252 0.2003 0.     0.2144 0.2229]
   [0.1869 0.2069 0.2144 0.     0.1879]
   [0.1623 0.2106 0.2229 0.1879 0.    ]]
  root@autodl-container-c47345924e-ebd10b47:~/autodl-tmp# 

• The ensemble strategies show particular effectiveness in improving generalization on unseen data

• Pairwise disagreement analysis confirms the diversity of models generated by both K-Fold and Snapshot methods

• train.py: Optimized training pipeline with K-Fold and Snapshot ensemble
• normal_train.py: Standard training pipeline for comparison
• utils.py: Utility functions for training, evaluation, and model selection
• model.py: Example model definition
• data/: Dataset directory (created automatically)
• checkpoints/: Directory for saved model checkpoints (created automatically)

• Author GitHub: https://github.com/Jackksonns

• Current limitations:

  • Primary focus on image classification tasks(more experiments are needed for different tasks)

• Future directions:

  • Extension to object detection, segmentation, and other computer vision tasks
  • Automated hyperparameter optimization