trainer-kit/DPO/f1_score_utils.py

"""
Utility for computing F1 scores at file level for ranking generated outputs.
This helps create preference pairs for DPO training.
"""

import json
import re
from typing import List, Set, Tuple, Dict
from pathlib import Path


def extract_files_from_selection(output_text: str) -> Set[str]:
    """
    Extract file paths from ##SELECT section.
    Expected format: modify::crates/path/to/file.rs::impl::ComponentName
    Returns set of unique file paths.
    """
    files = set()
    
    # Find ##SELECT section
    select_match = re.search(r'##SELECT\s*(.*?)<EOS>', output_text, re.DOTALL | re.IGNORECASE)
    if not select_match:
        return files
    
    select_section = select_match.group(1)
    
    # Extract file paths from each line
    # Format: action::path::type::name
    for line in select_section.strip().split('\n'):
        line = line.strip()
        if not line:
            continue
            
        # Split by :: and extract the file path (second component)
        parts = line.split('::')
        if len(parts) >= 2:
            file_path = parts[1]
            files.add(file_path)
    
    return files


def compute_file_level_f1(predicted: str, ground_truth: str) -> Dict[str, float]:
    """
    Compute F1 score based on file-level predictions.
    
    Args:
        predicted: Model output with ##SELECT section
        ground_truth: Ground truth output with ##SELECT section
    
    Returns:
        Dictionary with precision, recall, f1 scores
    """
    pred_files = extract_files_from_selection(predicted)
    gt_files = extract_files_from_selection(ground_truth)
    
    if len(gt_files) == 0:
        # No ground truth files
        if len(pred_files) == 0:
            return {"precision": 1.0, "recall": 1.0, "f1": 1.0}
        else:
            return {"precision": 0.0, "recall": 1.0, "f1": 0.0}
    
    if len(pred_files) == 0:
        # No predicted files but have ground truth
        return {"precision": 0.0, "recall": 0.0, "f1": 0.0}
    
    # Calculate metrics
    true_positives = len(pred_files & gt_files)
    false_positives = len(pred_files - gt_files)
    false_negatives = len(gt_files - pred_files)
    
    precision = true_positives / (true_positives + false_positives) if (true_positives + false_positives) > 0 else 0.0
    recall = true_positives / (true_positives + false_negatives) if (true_positives + false_negatives) > 0 else 0.0
    
    f1 = 2 * (precision * recall) / (precision + recall) if (precision + recall) > 0 else 0.0
    
    return {
        "precision": precision,
        "recall": recall,
        "f1": f1,
        "true_positives": true_positives,
        "false_positives": false_positives,
        "false_negatives": false_negatives,
        "pred_files": list(pred_files),
        "gt_files": list(gt_files),
    }


def rank_outputs_by_f1(outputs: List[str], ground_truth: str) -> List[Tuple[str, float, Dict]]:
    """
    Rank multiple outputs by their F1 scores compared to ground truth.
    
    Args:
        outputs: List of model outputs to rank
        ground_truth: Ground truth output
    
    Returns:
        List of tuples: (output, f1_score, metrics_dict) sorted by F1 descending
    """
    ranked = []
    for output in outputs:
        metrics = compute_file_level_f1(output, ground_truth)
        ranked.append((output, metrics["f1"], metrics))
    
    # Sort by F1 score descending
    ranked.sort(key=lambda x: x[1], reverse=True)
    return ranked


def create_dpo_pairs_from_generations(
    prompt: str,
    generations: List[str],
    ground_truth: str,
    min_f1_difference: float = 0.1
) -> List[Dict[str, str]]:
    """
    Create DPO training pairs from multiple generations.
    Uses F1 score to determine which generation is better.
    
    Args:
        prompt: Input prompt/task
        generations: List of generated outputs
        ground_truth: Ground truth output
        min_f1_difference: Minimum F1 difference to create a pair
    
    Returns:
        List of DPO pairs: {"prompt": str, "chosen": str, "rejected": str}
    """
    if len(generations) < 2:
        return []
    
    ranked = rank_outputs_by_f1(generations, ground_truth)
    pairs = []
    
    # Create pairs from ranked outputs
    for i in range(len(ranked)):
        for j in range(i + 1, len(ranked)):
            better_output, better_f1, _ = ranked[i]
            worse_output, worse_f1, _ = ranked[j]
            
            # Only create pair if F1 difference is significant
            if better_f1 - worse_f1 >= min_f1_difference:
                pairs.append({
                    "prompt": prompt,
                    "chosen": better_output,
                    "rejected": worse_output,
                    "chosen_f1": better_f1,
                    "rejected_f1": worse_f1,
                })
    
    return pairs


def convert_sft_to_dpo_with_sampling(
    sft_jsonl_path: str,
    output_jsonl_path: str,
    model_inference_fn,
    num_samples: int = 4,
    min_f1_difference: float = 0.1,
    temperature: float = 0.8
):
    """
    Convert SFT dataset to DPO dataset by sampling multiple outputs and ranking by F1.
    
    Args:
        sft_jsonl_path: Path to SFT JSONL file
        output_jsonl_path: Path to output DPO JSONL file
        model_inference_fn: Function that takes (prompt, num_samples, temperature) and returns List[str]
        num_samples: Number of outputs to sample per prompt
        min_f1_difference: Minimum F1 difference to create a pair
        temperature: Sampling temperature
    """
    pairs_created = 0
    
    with open(sft_jsonl_path, 'r') as f_in, open(output_jsonl_path, 'w') as f_out:
        for line in f_in:
            data = json.loads(line)
            
            # Extract prompt and ground truth
            prompt = data.get("input", "")
            ground_truth = data.get("output", "")
            
            if not prompt or not ground_truth:
                continue
            
            # Generate multiple outputs
            try:
                generations = model_inference_fn(prompt, num_samples, temperature)
            except Exception as e:
                print(f"Error generating outputs: {e}")
                continue
            
            # Create DPO pairs
            pairs = create_dpo_pairs_from_generations(
                prompt, generations, ground_truth, min_f1_difference
            )
            
            # Write pairs to output
            for pair in pairs:
                f_out.write(json.dumps(pair) + '\n')
                pairs_created += 1
    
    print(f"Created {pairs_created} DPO pairs from {sft_jsonl_path}")


def prepare_dpo_data_from_instruct(
    instruct_jsonl: str,
    output_dpo_jsonl: str,
):
    """
    Simple conversion from instruction data to DPO format.
    This assumes you already have multiple outputs per input or will generate them.
    
    For demonstration, this creates a basic structure. In practice, you need to:
    1. Generate multiple outputs for each input
    2. Rank them by F1 score
    3. Create chosen/rejected pairs
    """
    print(f"Converting {instruct_jsonl} to DPO format...")
    print("Note: This requires generating multiple outputs per prompt.")
    print("Use convert_sft_to_dpo_with_sampling() with your model for actual conversion.")
    
    # Example structure - you'll need to fill this with actual generations
    with open(instruct_jsonl, 'r') as f:
        for line in f:
            data = json.loads(line)
            print(f"Input: {data.get('input', '')[:100]}...")
            print(f"Ground truth output available: {len(data.get('output', ''))} chars")
            print("  -> Need to generate multiple outputs and rank by F1 score")
            print()
            break  # Just show one example


if __name__ == "__main__":
    # Example usage
    print("F1 Score Utility for File-Level Ranking")
    print("=" * 50)
    
    # Example 1: Compute F1 for two outputs
    ground_truth = """
##OUTPUT
The webhook system requires subscription support.
##SELECT
crates/common_enums/src/enums.rs::EventClass
crates/router/src/webhooks.rs::process_webhook
<EOS>
"""
    
    prediction1 = """
##OUTPUT
The webhook system requires subscription support.
##SELECT
crates/common_enums/src/enums.rs::EventClass
crates/router/src/webhooks.rs::process_webhook
<EOS>
"""
    
    prediction2 = """
##OUTPUT
The webhook system requires subscription support.
##SELECT
crates/common_enums/src/enums.rs::EventClass
crates/router/src/handlers.rs::handle_request
<EOS>
"""
    
    print("\nExample 1: Perfect match")
    metrics1 = compute_file_level_f1(prediction1, ground_truth)
    print(f"F1 Score: {metrics1['f1']:.3f}")
    print(f"Precision: {metrics1['precision']:.3f}, Recall: {metrics1['recall']:.3f}")
    
    print("\nExample 2: Partial match")
    metrics2 = compute_file_level_f1(prediction2, ground_truth)
    print(f"F1 Score: {metrics2['f1']:.3f}")
    print(f"Precision: {metrics2['precision']:.3f}, Recall: {metrics2['recall']:.3f}")
    
    print("\nExample 3: Ranking outputs")
    outputs = [prediction1, prediction2]
    ranked = rank_outputs_by_f1(outputs, ground_truth)
    print("Ranked outputs:")
    for i, (output, f1, metrics) in enumerate(ranked, 1):
        print(f"  {i}. F1={f1:.3f} - {metrics['true_positives']} correct files")