Journal of Bionic Engineering (2025) 22:1434–1458 https://doi.org/10.1007/s42235-025-00673-0

Swarm-based Cost-sensitive Decision Tree Using Optimized Rules for Imbalanced Data Classification

Mehdi Mansouri1,2 · Mohammad H. Nadimi-Shahraki1,2  · Zahra Beheshti1,2

1 Faculty of Computer Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan, Iran 

2 Big Data Research Center, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan, Iran

Abstract 

Despite the widespread use of Decision trees (DT) across various applications, their performance tends to suffer when dealing with imbalanced datasets, where the distribution of certain classes significantly outweighs others. Cost-sensitive learning is a strategy to solve this problem, and several cost-sensitive DT algorithms have been proposed to date. However, existing algorithms, which are heuristic, tried to greedily select either a better splitting point or feature node, leading to local optima for tree nodes and ignoring the cost of the whole tree. In addition, determination of the costs is difficult and often requires domain expertise. This study proposes a DT for imbalanced data, called Swarm-based Cost-sensitive DT (SCDT), using the cost-sensitive learning strategy and an enhanced swarm-based algorithm. The DT is encoded using a hybrid individual representation. A hybrid artificial bee colony approach is designed to optimize rules, considering specified costs in an F-Measure-based fitness function. Experimental results using datasets compared with state-of-the-art DT algorithms show that the SCDT method achieved the highest performance on most datasets. Moreover, SCDT also excels in other critical performance metrics, such as recall, precision, F1-score, and AUC, with notable results with average values of 83%, 87.3%, 85%, and 80.7%, respectively. 

Keywords Decision tree · Cost-sensitive learning · Artificial bee colony · Swarm-based · Imbalanced classification