Automatically synthesize and optimize training data using GRPO to generate data recipes (specifications for dataset creation). Use a Data Verifier to efficiently evaluate sample quality without full model training. Achieve performance comparable to human expert curation across diverse domains.
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Automatically synthesize and optimize training data using GRPO to generate data recipes (specifications for dataset creation). Use a Data Verifier to efficiently evaluate sample quality without full model training. Achieve performance comparable to human expert curation across diverse domains.
DataChef: Cooking Up Optimal Data Recipes via RL
Problem Context
Creating high-quality training data is labor-intensive and requires domain expertise. DataChef automates this by using RL to generate data recipes—specifications for how to create training datasets. A fast Data Verifier (rubric-based classifier) provides rewards without expensive downstream training, enabling rapid iteration on dataset composition.
Core Concept
DataChef operates in two phases: (1) cold-start with supervised demonstrations from strong models, (2) RL phase where policies generate data recipes, verifiers assess quality, and GRPO optimizes recipe generation. Recipes specify: data source selection, augmentation strategies, filtering criteria, and mixing ratios.
"""
Generate data recipe for task.
Args:
task: Task description
max_tokens: Recipe generation length
Returns:
recipe_dict: Parsed recipe specification
"""
f"""Generate a data recipe for training on: {task}
Specify:
1. Data sources (wikipedia, books, web, etc.)
2. Augmentation strategies (paraphrase, back_translation, etc.)
3. Quality filters (minimum length, diversity, etc.)
4. Mixing ratios for different sources
5. Target sample size
Format as JSON.
Data recipe:"""
self
0.7
# Parse recipe
try
except
# Fallback: extract fields from free text
self
return
def
_parse_recipe_freetext
self, text: str
Dict
"""Fallback parsing from free text."""
return
'sources'
'wikipedia'
'augmentation'
'paraphrase'
'filters'
'min_length'
10
'mixing'
'wikipedia'
1.0
'size'
10000
Step 2: Data verifier (fast quality assessment)
classDataVerifier:
"""Fast quality assessment without full model training."""def__init__(self, quality_rubric: Dict = None):
"""
Args:
quality_rubric: Scoring criteria for samples
"""self.rubric = quality_rubric or {
'invalid': 0.0,
'format_error': 0.1,
'incorrect': 0.2,
'task_mismatch': 0.5,
'pass': 1.0
}
defverify_sample(
self,
sample: Dict,
task: str,
verifier_model=None) -> float:
"""
Classify sample quality quickly.
Args:
sample: Training sample (input, target)
task: Task description
verifier_model: Optional LLM for semantic checking
Returns:
score: Quality score (0-1)
"""# Format checkif'input'notin sample or'target'notin sample:
returnself.rubric['format_error']
input_text = sample['input']
target_text = sample['target']
# Length checkiflen(input_text.split()) < 5orlen(target_text.split()) < 1:
returnself.rubric['format_error']
# Task relevance check (simple heuristic)ifnotself._is_task_relevant(input_text, task):
returnself.rubric['task_mismatch']
# Correctness estimationif verifier_model:
is_correct = verifier_model.verify(input_text, target_text)
if is_correct:
returnself.rubric['pass']
else:
returnself.rubric['incorrect']
# Default: assume correct if format is validreturnself.rubric['pass']
def_is_task_relevant(self, text: str, task: str) -> bool:
"""Check task relevance (simplified)."""
task_keywords = task.lower().split()
text_lower = text.lower()
returnany(kw in text_lower for kw in task_keywords[:3])
defverify_dataset(
self,
dataset: List[Dict],
task: str,
sample_fraction: float = 0.1) -> float:
"""
Estimate dataset quality via sampling.
Args:
dataset: Full dataset
sample_fraction: Fraction to verify
Returns:
avg_quality_score: Mean quality across sample
"""import random
sample_size = max(1, int(len(dataset) * sample_fraction))
sample = random.sample(dataset, min(sample_size, len(dataset)))
scores = [self.verify_sample(s, task) for s in sample]
returnsum(scores) / len(scores)
Step 3: GRPO training for recipe generation
classDataRecipeRL:
"""GRPO-based optimization of data recipes."""def__init__(
self,
model,
optimizer,
verifier: DataVerifier,
data_executor,
group_size: int = 4):
self.model = model
self.optimizer = optimizer
self.verifier = verifier
self.executor = data_executor # Creates datasets from recipesself.group_size = group_size
self.recipe_generator = DataRecipeGenerator(model)
defcompute_recipe_reward(
self,
recipe: Dict,
task: str,
downstream_verifier=None) -> float:
"""
Compute reward for recipe.
Args:
recipe: Generated recipe
task: Task for which data is created
downstream_verifier: Optional model for full eval
Returns:
reward: Quality score
"""try:
# Execute recipe: create dataset
dataset = self.executor.create_dataset(recipe, task, sample_size=100)
# Verify dataset
quality_score = self.verifier.verify_dataset(dataset, task)
# Normalize reward
reward = quality_score
except Exception as e:
# Recipe failed to execute
reward = 0.0return reward
deftraining_step(
self,
tasks: List[str],
batch_size: int = 4) -> Dict:
"""Single training step."""
log_probs_list = []
rewards = []
for task in tasks[:batch_size]:
# Generate recipe
recipe, log_probs = self.recipe_generator.generate_recipe(task)
log_probs_list.append(log_probs)
# Compute reward
reward = self.compute_recipe_reward(recipe, task)
rewards.append(reward)
log_probs = torch.stack(log_probs_list)
rewards = torch.tensor(rewards, dtype=torch.float32)
# GRPO loss
log_prob_ratio = log_probs - log_probs.detach()
ratio = torch.exp(log_prob_ratio)
# Group relative advantage
group_mean_reward = rewards.mean()
relative_rewards = rewards - group_mean_reward
clipped_ratio = torch.clamp(ratio, 0.5, 2.0)
loss = -torch.min(
log_prob_ratio * relative_rewards.unsqueeze(-1),
torch.log(clipped_ratio) * relative_rewards.unsqueeze(-1)
).mean()
# Updateself.optimizer.zero_grad()
loss.backward()
torch.nn.utils.clip_grad_norm_(self.model.parameters(), 1.0)
self.optimizer.step()
return {
'loss': loss.item(),
'avg_reward': rewards.mean().item(),
'avg_quality': rewards.mean().item()
}
Step 4: Cold-start with synthetic demonstrations
defgenerate_cold_start_demonstrations(
strong_model,
tasks: List[str],
num_demos_per_task: int = 5) -> List[Dict]:
"""
Generate high-quality data recipes from strong model.
Uses strong model (e.g., GPT-4) to create initial demonstrations.
"""
demonstrations = []
for task in tasks:
for _ inrange(num_demos_per_task):
# Ask strong model to create data recipe
prompt = f"""Create a high-quality data recipe for: {task}
Consider data sources, augmentation, filtering, and quality thresholds.
Return as a concrete JSON specification."""
recipe_json = strong_model.generate(prompt, max_tokens=300)
demo = {
'task': task,
'recipe': recipe_json,
'is_high_quality': True
}
demonstrations.append(demo)
return demonstrations
deftrain_datachef_with_cold_start(
model,
strong_model,
tasks: List[str],
data_executor,
optimizer,
num_epochs: int = 10,
num_rl_steps_per_epoch: int = 100):
"""
Full DataChef training: cold-start SFT → RL.
"""# Cold-startprint("Cold-start: Supervised fine-tuning")
demos = generate_cold_start_demonstrations(strong_model, tasks, num_demos_per_task=5)
for demo in demos:
prompt = f"Task: {demo['task']}\n\nData recipe:"
target = demo['recipe']
# SFT loss (simplified)# Would compute cross-entropy on tokens# RL phaseprint("RL phase: GRPO optimization")
verifier = DataVerifier()
rl_trainer = DataRecipeRL(model, optimizer, verifier, data_executor)
for epoch inrange(num_epochs):
total_loss = 0.0
total_reward = 0.0for step inrange(num_rl_steps_per_epoch):
metrics = rl_trainer.training_step(tasks, batch_size=4)
total_loss += metrics['loss']
total_reward += metrics['avg_reward']
avg_loss = total_loss / num_rl_steps_per_epoch
avg_reward = total_reward / num_rl_steps_per_epoch
print(f"Epoch {epoch + 1}: Loss={avg_loss:.4f}, Reward={avg_reward:.4f}")
return model
Practical Guidance
When to use: Data curation bottleneck; need diverse training data; frequent dataset regeneration
Hyperparameters:
verification_sample_fraction: 0.05-0.2 (tradeoff: cost vs. confidence)
group_size: 4-8 (GRPO)
cold_start_demos: 3-10 per task
recipe_max_tokens: 200-400
Key advantages:
Automates data curation (labor savings)
Fast verification without full training
Curriculum: SFT → RL smooths learning
Generalizes across domains
Common pitfalls:
Verifier too lenient → low-quality recipes
Not validating executor can actually create dataset
Cold-start too brief → RL starts from bad initialization
Recipe too constrained → fails to explore
Scaling: Verification cost is the main bottleneck; parallelize across tasks.
Reference
Paper: https://arxiv.org/abs/2602.11089
Related work: Data augmentation, dataset curation, GRPO
Benchmarks: Diverse domains including math, code, QA
