Evaluating synthetic data involves applying a diverse set of metrics across fidelity, utility, and privacy dimensions, as detailed in previous chapters. Performing these evaluations manually for every new synthetic dataset or generative model variant quickly becomes inefficient, error-prone, and difficult to reproduce. Automating the evaluation process addresses these challenges, providing a systematic, scalable, and reliable approach to quality assessment.
An automated evaluation pipeline is essentially a workflow or script that programmatically executes a predefined sequence of quality checks on input real and synthetic datasets, collects the results, and often formats them for reporting. The primary motivations for building such pipelines include:
A typical automated evaluation pipeline consists of several distinct stages:
Several approaches can be used to implement automated evaluation pipelines, ranging from simple scripts to sophisticated workflow management systems.
1. Python Scripting: For simpler cases, a well-structured Python script using libraries like Pandas, NumPy, SciPy, Scikit-learn, and specialized synthetic data evaluation libraries (such as SDMetrics, Synthcity, or custom implementations) can suffice. Modularity is important here; encapsulate different metric calculations into separate functions or classes.
import pandas as pd
# Assume functions like run_statistical_tests, run_tstr_evaluation, run_privacy_checks exist
# These functions would encapsulate logic from previous chapters
# Example: from statistical_tests import compare_distributions
# Example: from ml_utility import evaluate_tstr
# Example: from privacy_tests import run_mia
def load_data(real_path, synthetic_path):
"""Loads real and synthetic data."""
real_data = pd.read_csv(real_path)
synthetic_data = pd.read_csv(synthetic_path)
# Basic validation or preprocessing could happen here
print(f"Loaded Real Data: {real_data.shape}")
print(f"Loaded Synthetic Data: {synthetic_data.shape}")
return real_data, synthetic_data
def run_evaluation_pipeline(config):
"""Runs the configured evaluation pipeline."""
real_data, synthetic_data = load_data(config['data']['real'], config['data']['synthetic'])
results = {}
if config['evaluations']['statistical_fidelity']['enabled']:
print("Running Statistical Fidelity tests...")
# Example: Replace with actual function call
# results['statistical'] = run_statistical_tests(
# real_data, synthetic_data,
# config['evaluations']['statistical_fidelity']['tests']
# )
results['statistical'] = {"KS_complement_mean": 0.85, "Corr_diff": 0.05} # Placeholder
print("Statistical Fidelity tests complete.")
if config['evaluations']['ml_utility']['enabled']:
print("Running ML Utility tests (TSTR)...")
# Example: Replace with actual function call
# results['ml_utility'] = run_tstr_evaluation(
# real_data, synthetic_data,
# config['evaluations']['ml_utility']['models'],
# config['evaluations']['ml_utility']['target_column']
# )
results['ml_utility'] = {"LogisticRegression_AUC_diff": 0.02, "RandomForest_F1_diff": 0.03} # Placeholder
print("ML Utility tests complete.")
if config['evaluations']['privacy']['enabled']:
print("Running Privacy tests...")
# Example: Replace with actual function call
# results['privacy'] = run_privacy_checks(
# real_data, synthetic_data,
# config['evaluations']['privacy']['attacks']
# )
results['privacy'] = {"MIA_advantage": 0.12, "DCR": 0.98} # Placeholder
print("Privacy tests complete.")
print("Pipeline finished. Aggregated results:")
print(results)
return results
# Example configuration (could be loaded from a YAML/JSON file)
pipeline_config = {
'data': {
'real': 'path/to/real_data.csv',
'synthetic': 'path/to/synthetic_data.csv'
},
'evaluations': {
'statistical_fidelity': {'enabled': True, 'tests': ['ks_complement', 'correlation_diff']},
'ml_utility': {'enabled': True, 'models': ['LogisticRegression', 'RandomForest'], 'target_column': 'target'},
'privacy': {'enabled': True, 'attacks': ['basic_mia', 'dcr']}
}
}
# Execute the pipeline
evaluation_results = run_evaluation_pipeline(pipeline_config)
# Results could then be saved to JSON, CSV, or used for plotting
import json
with open('evaluation_results.json', 'w') as f:
json.dump(evaluation_results, f, indent=4)
2. Workflow Orchestration Tools: For more complex scenarios involving multiple dependent steps, parallel execution, scheduling, or robust error handling, dedicated workflow orchestrators are highly beneficial. Tools like Apache Airflow, Kubeflow Pipelines, Prefect, or Dagster allow you to define your evaluation pipeline as a Directed Acyclic Graph (DAG) of tasks.
A simple DAG representing an evaluation pipeline structure, suitable for implementation with workflow orchestrators. Tasks like statistical fidelity, ML utility, and privacy can often run in parallel after data loading.
These tools provide features like:
3. Containerization (Docker): Regardless of the implementation approach (scripts or orchestrators), using containers (like Docker) is highly recommended. Containerization packages your code, dependencies (Python libraries, system tools), and configurations into a self-contained unit. This ensures that the evaluation environment is identical wherever the pipeline is run, solving the common "it works on my machine" problem and enhancing reproducibility.
requirements.txt
or environment.yml
). Consider versioning your configuration files as well.By automating the evaluation process, you establish a robust framework for consistently assessing synthetic data quality. The structured outputs generated by these pipelines are the direct inputs for the visualization and interpretation techniques discussed next, enabling efficient and informed decision-making about the suitability of synthetic datasets.
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