inspect_yolo_model.py

"""
Script to inspect a YOLO .pt model and determine its variant (nano, small, medium, large, xlarge).
"""
import argparse
from pathlib import Path
import torch
from ultralytics import YOLO


def inspect_yolo_model(model_path: Path):
    """Inspect YOLO model to determine variant and architecture details."""
    print(f"Inspecting model: {model_path}")
    print("=" * 60)
    
    # Method 1: Load with Ultralytics and check metadata
    try:
        model = YOLO(str(model_path))
        
        # Check model info
        print("\n--- Model Information ---")
        print(f"Model type: {type(model.model)}")
        
        # Try to get model name from metadata
        if hasattr(model, 'model') and hasattr(model.model, 'yaml'):
            yaml_path = model.model.yaml
            print(f"YAML config: {yaml_path}")
            if yaml_path:
                # Extract variant from yaml path
                yaml_name = Path(yaml_path).stem if isinstance(yaml_path, (str, Path)) else str(yaml_path)
                print(f"YAML name: {yaml_name}")
                # Common patterns: yolo11n.yaml, yolo11s.yaml, yolo11m.yaml, yolo11l.yaml, yolo11x.yaml
                # or yolov8n.yaml, yolov8s.yaml, etc.
                if 'n' in yaml_name.lower():
                    variant = "Nano (n)"
                elif 's' in yaml_name.lower():
                    variant = "Small (s)"
                elif 'm' in yaml_name.lower():
                    variant = "Medium (m)"
                elif 'l' in yaml_name.lower():
                    variant = "Large (l)"
                elif 'x' in yaml_name.lower():
                    variant = "XLarge (x)"
                else:
                    variant = "Unknown"
                print(f"Detected variant: {variant}")
        
        # Check model metadata if available
        if hasattr(model.model, 'names'):
            print(f"Number of classes: {len(model.model.names)}")
            print(f"Class names: {list(model.model.names.values())[:5]}...")  # Show first 5
        
        # Get model info summary
        print("\n--- Model Summary ---")
        try:
            info = model.info(verbose=False)
            print(info)
        except:
            pass
        
        # Count parameters
        if hasattr(model.model, 'parameters'):
            total_params = sum(p.numel() for p in model.model.parameters())
            trainable_params = sum(p.numel() for p in model.model.parameters() if p.requires_grad)
            print(f"\n--- Parameter Count ---")
            print(f"Total parameters: {total_params:,}")
            print(f"Trainable parameters: {trainable_params:,}")
            
            # Rough estimates for YOLO variants (these vary by version but give a ballpark)
            if total_params < 3_000_000:
                size_estimate = "Nano (n) - typically < 3M params"
            elif total_params < 12_000_000:
                size_estimate = "Small (s) - typically 3-12M params"
            elif total_params < 26_000_000:
                size_estimate = "Medium (m) - typically 12-26M params"
            elif total_params < 44_000_000:
                size_estimate = "Large (l) - typically 26-44M params"
            else:
                size_estimate = "XLarge (x) - typically > 44M params"
            print(f"Size estimate: {size_estimate}")
        
    except Exception as e:
        print(f"Error loading with Ultralytics: {e}")
        print("\nTrying alternative method...")
    
    # Method 2: Direct PyTorch inspection
    print("\n" + "=" * 60)
    print("--- Direct PyTorch Inspection ---")
    try:
        checkpoint = torch.load(str(model_path), map_location='cpu')
        
        # Check for metadata
        if 'model' in checkpoint:
            model_dict = checkpoint['model']
            if isinstance(model_dict, dict):
                # Look for architecture hints in state dict keys
                print("Checking state dict keys for architecture hints...")
                keys = list(model_dict.keys())[:10]  # First 10 keys
                for key in keys:
                    print(f"  {key}")
                
                # Count layers
                layer_count = len([k for k in model_dict.keys() if 'weight' in k or 'bias' in k])
                print(f"\nTotal weight/bias tensors: {layer_count}")
        
        # Check checkpoint metadata
        if 'epoch' in checkpoint:
            print(f"Training epoch: {checkpoint.get('epoch', 'N/A')}")
        if 'best_fitness' in checkpoint:
            print(f"Best fitness: {checkpoint.get('best_fitness', 'N/A')}")
        
        # File size
        file_size_mb = model_path.stat().st_size / (1024 * 1024)
        print(f"\nModel file size: {file_size_mb:.2f} MB")
        
        # Rough size estimates based on file size (very approximate)
        if file_size_mb < 6:
            size_estimate = "Likely Nano (n) - file < 6MB"
        elif file_size_mb < 22:
            size_estimate = "Likely Small (s) - file 6-22MB"
        elif file_size_mb < 50:
            size_estimate = "Likely Medium (m) - file 22-50MB"
        elif file_size_mb < 85:
            size_estimate = "Likely Large (l) - file 50-85MB"
        else:
            size_estimate = "Likely XLarge (x) - file > 85MB"
        print(f"Size estimate from file: {size_estimate}")
        
    except Exception as e:
        print(f"Error with direct PyTorch inspection: {e}")
    
    print("\n" + "=" * 60)
    print("Inspection complete!")


def main():
    parser = argparse.ArgumentParser(
        description="Inspect YOLO .pt model to determine variant"
    )
    parser.add_argument(
        "--model_path",
        type=Path,
        help="Path to YOLO .pt model file"
    )
    args = parser.parse_args()
    
    if not args.model_path.exists():
        print(f"Error: Model file not found: {args.model_path}")
        return
    
    inspect_yolo_model(args.model_path)


if __name__ == "__main__":
    main()