Functional Random Forest with Adaptive Cost-Sensitive Splitting for Imbalanced Functional Data Classification

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Hauptverfasser: Mostafa, Fahad, Khan, Hafiz
Format: Preprint
Veröffentlicht: 2025
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author Mostafa, Fahad
Khan, Hafiz
author_facet Mostafa, Fahad
Khan, Hafiz
contents Classification of functional data where observations are curves or trajectories poses unique challenges, particularly under severe class imbalance. Traditional Random Forest algorithms, while robust for tabular data, often fail to capture the intrinsic structure of functional observations and struggle with minority class detection. This paper introduces Functional Random Forest with Adaptive Cost-Sensitive Splitting (FRF-ACS), a novel ensemble framework designed for imbalanced functional data classification. The proposed method leverages basis expansions and Functional Principal Component Analysis (FPCA) to represent curves efficiently, enabling trees to operate on low dimensional functional features. To address imbalance, we incorporate a dynamic cost sensitive splitting criterion that adjusts class weights locally at each node, combined with a hybrid sampling strategy integrating functional SMOTE and weighted bootstrapping. Additionally, curve specific similarity metrics replace traditional Euclidean measures to preserve functional characteristics during leaf assignment. Extensive experiments on synthetic and real world datasets including biomedical signals and sensor trajectories demonstrate that FRF-ACS significantly improves minority class recall and overall predictive performance compared to existing functional classifiers and imbalance handling techniques. This work provides a scalable, interpretable solution for high dimensional functional data analysis in domains where minority class detection is critical.
format Preprint
id arxiv_https___arxiv_org_abs_2512_07888
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Functional Random Forest with Adaptive Cost-Sensitive Splitting for Imbalanced Functional Data Classification
Mostafa, Fahad
Khan, Hafiz
Machine Learning
Artificial Intelligence
Applications
Computation
62H30, 62G05, 68T05, 62P10
Classification of functional data where observations are curves or trajectories poses unique challenges, particularly under severe class imbalance. Traditional Random Forest algorithms, while robust for tabular data, often fail to capture the intrinsic structure of functional observations and struggle with minority class detection. This paper introduces Functional Random Forest with Adaptive Cost-Sensitive Splitting (FRF-ACS), a novel ensemble framework designed for imbalanced functional data classification. The proposed method leverages basis expansions and Functional Principal Component Analysis (FPCA) to represent curves efficiently, enabling trees to operate on low dimensional functional features. To address imbalance, we incorporate a dynamic cost sensitive splitting criterion that adjusts class weights locally at each node, combined with a hybrid sampling strategy integrating functional SMOTE and weighted bootstrapping. Additionally, curve specific similarity metrics replace traditional Euclidean measures to preserve functional characteristics during leaf assignment. Extensive experiments on synthetic and real world datasets including biomedical signals and sensor trajectories demonstrate that FRF-ACS significantly improves minority class recall and overall predictive performance compared to existing functional classifiers and imbalance handling techniques. This work provides a scalable, interpretable solution for high dimensional functional data analysis in domains where minority class detection is critical.
title Functional Random Forest with Adaptive Cost-Sensitive Splitting for Imbalanced Functional Data Classification
topic Machine Learning
Artificial Intelligence
Applications
Computation
62H30, 62G05, 68T05, 62P10
url https://arxiv.org/abs/2512.07888