Feature Subset Selection with Hybrids of Filters and Evolutionary Algorithms

Summary. The performance of classification algorithms is affected by the features used to describe the labeled examples presented to the inducers. Therefore, the problem of feature subset selection has received considerable attention. Approaches to this problem based on evolutionary algorithms (EAs) typically use the wrapper method, treating the inducer as a black box that is used to evaluate candidate feature subsets. However, the evaluations might take a considerable time and the wrapper approach might be impractical for large data sets. Alternative filter methods use heuristics to select feature subsets from the data and are usually considered more scalable than wrappers to the dimensionality and volume of the data. This chapter describes hybrids of evolutionary algorithms (EAs) and filter methods applied to the selection of feature subsets for classification problems. The proposed hybrids were compared against each of their components, two feature selection wrappers that are in wide use, and another filter-wrapper hybrid. The objective of this chapter is to determine if the proposed evolutionary hybrids present advantages over the other methods in terms of accuracy or speed. The experiments used are decision tree and naive Bayes (NB) classifiers on public-domain and artificial data sets. The experimental results suggest that the evolutionary hybrids usually find compact feature subsets that result in the most accurate classifiers, while beating the execution time of the other wrappers.