ftir-prep 0.3.1

A framework for designing and evaluating optimal preprocessing pipelines for FTIR spectral data used in classification tasks. It provides modular implementations of common preprocessing techniques and allows automated exploration of preprocessing combinations to enhance model performance.

FTIR-Prep: FTIR Preprocessing Framework

A modular and extensible framework for optimizing FTIR preprocessing pipelines for disease diagnosis.

🚀 Features

• Modular: Component-based reusable architecture
• Extensible: Easy addition of new preprocessing techniques
• Automatic Optimization: Optuna integration for optimal preprocessing pipeline search
• Robust Validation: Support for group-based cross-validation
• Configurable: Flexible pipeline configuration system
• Documented: Complete documentation with practical examples

📋 Supported Preprocessing Techniques

🔧 Baseline Correction

• Rubberband: Automatic correction using rubberband algorithm
• Polynomial: Correction using configurable order polynomials (1-6)
• Whittaker: Penalized least squares smoothing with lambda parameter
• ALS: Asymmetric Least Squares with lambda and p parameters
• ArPLS: Adaptive reweighted penalized least squares
• DrPLS: Doubly reweighted penalized least squares
• GCV Spline: Generalized cross-validation spline smoothing
• Gaussian Process: Baseline correction using Gaussian processes

📊 Normalization

• Min-Max: Individual Min-Max spectrum normalization
• Vector: L1, L2, or maximum normalization
• Amida I: Normalization based on amide I band peak (1600-1700 cm⁻¹)
• Area: Area under curve normalization

🎯 Smoothing

• Savitzky-Golay: Polynomial filter with configurable parameters
• Wavelets: Denoising using Daubechies wavelets (db2, db3, db4)
• Local Polynomial: LOWESS smoothing with configurable bandwidth
• Whittaker: Penalized least squares smoothing
• GCV Spline: Generalized cross-validation spline smoothing
• Flat: Flat window convolution smoothing
• Hanning: Hanning window convolution smoothing

📈 Derivatives

• First Derivative: First derivative calculation via Savitzky-Golay (order 1)
• Second Derivative: Second derivative calculation via Savitzky-Golay (order 2)

✂️ Wavelength Truncation

• Fingerprint Region: Keep only fingerprint region (900-1800 cm⁻¹)
• Fingerprint + Lipids: Keep fingerprint and lipids regions (900-1800, 2800-3050 cm⁻¹)

🔍 Model Explainability

• SHAP Analysis: Feature importance analysis using SHAP values

🏗️ Architecture

ftir_prep/
├── core/                    # Core functionalities
│   ├── pipeline.py         # Preprocessing pipeline
│   ├── evaluator.py        # Pipeline evaluation
│   └── explainer.py        # SHAP explainability analysis
├── preprocessing/           # Preprocessing techniques
│   ├── baseline.py         # Baseline correction
│   ├── normalization.py    # Normalization
│   ├── smoothing.py        # Smoothing
│   ├── derivatives.py      # Derivative calculation
│   └── truncation.py      # Wavelength truncation
├── optimization/            # Automatic optimization
│   └── optuna_optimizer.py # Optuna integration
├── utils/                   # Utilities
│   └── data_loader.py      # Data loading
└── config/                  # Configurations
    └── settings.py         # Default parameters

🚀 Installation

Requirements

• Python 3.8+
• pip (usually included with Python)

Installation via PyPI (Recommended - Simplest)

pip install ftir-prep

📖 Basic Usage

1. Data Loading

1.1 Separates into groups to guarantee that data from the same patient will be in the same fold in a future classification task

from ftir_prep import FTIRDataLoader

# Load FTIR data
data_loader = FTIRDataLoader(
    data_path="ftir_data.dat",
    wavenumbers_path="wavenumbers.dat"
)

X, y, wavenumbers = data_loader.load_data()

# Create groups var that will be used in classification task to indicate that patient's data must be in the same fold
groups = data_loader.create_groups(instances_per_group=3)

1.2 Slices the data to use only one spectra per patient. Data must be ordered by patient

from ftir_prep import FTIRDataLoader

# Load FTIR data
data_loader = FTIRDataLoader(
    data_path="ftir_data.dat",
    wavenumbers_path="wavenumbers.dat"
)

X, y, wavenumbers = data_loader.load_data(slice_size = 3) #use one of the triplicated spectra per patient

2. Pipeline Creation

from ftir_prep import FTIRPipeline, PipelineBuilder

# Using direct configuration
pipeline = FTIRPipeline()
pipeline.add_step('truncation', 'fingerprint_lipids')
pipeline.add_step('baseline', 'polynomial', polynomial_order=2)
pipeline.add_step('normalization', 'vector')


# Using PipelineBuilder (Fluent API)
pipeline = (PipelineBuilder()
            .add_truncation('fingerprint_lipids')
            .add_baseline('rubberband')
            .add_normalization('minmax')
            .add_smoothing('savgol', polyorder=2)
            .add_derivative('savgol',order=1)
            .build())

3. Execution and Evaluation

from ftir_prep import PipelineEvaluator

# Process data
X_processed, wavenumbers_processed = pipeline.process(X, wavenumbers)

# Evaluate pipeline
evaluator = PipelineEvaluator(classifier=None, # use default Random Forest
                              cv_method='StratifiedGroupKFold', # cross-validation strategy
                              cv_params={'n_splits': 3, #folds
                                        'shuffler': False,
                                        'random_state': 42})
results = evaluator.evaluate_pipeline(pipeline,
                                      X, y,
                                      groups, # groups var created previously
                                      wavenumbers=wavenumbers
)

print(f"Accuracy: {results['mean_accuracy']:.4f} ± {results['std_accuracy']:.4f}")

4. Automatic Optimization

from ftir_prep import OptunaPipelineOptimizer

# Automatically optimize parameters
optimizer = OptunaPipelineOptimizer(X, y, 
                                    wavenumbers,
                                    groups,
                                    evaluator=evaluator, # previously configured PipelineEvaluator object
                                    metric='f1_macro')
study = optimizer.optimize(n_trials=30)

best_pipeline = optimizer.best_pipeline
best_pipeline.save_pipeline("best_pipeline_found.json") # Saves the best pipeline found in a json file
print("Best pipeline saved to 'best_pipeline_found.json'")

# Save optimization metadata
metadata = optimizer.get_metadata()
metadata.to_csv("optimization_metadata.csv")

5. Model Explainability

from ftir_prep import FTIRExplainer

# Create explainer
explainer = FTIRExplainer(classifier=your_classifier)

# Analyze feature importance with SHAP
# It will save in output_dir a csv and a png with feature importance data
results = explainer.explain_model(
    X_processed, y, groups,
    split_method='stratified_group',
    feature_names=wavenumbers_processed,
    output_dir="shap_analysis"
)

🔬 Practical Examples

Pipeline Creation Examples

# Direct configuration example
python3 examples/create_pipeline/direct_configuration.py

# PipelineBuilder (Fluent API) example
python3 examples/create_pipeline/pipeline_builder.py

Pipeline Comparison Example

# Compare different preprocessing strategies
python3 examples/compare_pipelines/compare_pipelines.py

Pipeline Optimization Example

# Automatic pipeline optimization
python3 examples/pipeline_search/pipeline_search.py

Pipeline Loading Example

# Load and use saved pipelines
python3 examples/read_pipeline_from_file/read_pipeline_file.py

SHAP Explainability Example

# Feature importance analysis with SHAP
python3 examples/shap_analysis/explainer_example.py

🎯 Use Cases

Disease Diagnosis

• Analysis of FTIR spectra from biological samples
• Biomarker identification
• Automatic sample classification

Scientific Research

• Methodology comparison
• Protocol optimization
• Result validation

📚 Documentation

• Docstrings: Complete inline documentation
• Examples: Functional example code

👥 Authors

• Lucas Mendonça - Initial development - GitHub

⭐ If this project was useful to you, consider giving it a star on GitHub!