TABLE 1.

Comparison of existing reviews with the current survey.

References	Description	Shortcomings
Kumar et al., 2017	The survey focuses on the Supervised Gene Selection methods on Cancer Microarray dataset.	Concentrates only on Supervised Gene Selection methods.
Sheikhpour et al., 2017	The work discusses various works done in the Semi-Supervised Gene Selection methods, and the hierarchical structure of semi-supervised methods is also focused.	Concentrates only on Semi-Supervised Gene Selection methods.
Wang et al., 2016	The work focuses on the gene selection methods from a search strategy perspective.	Concentrates on search strategies in the feature selection methods.
Lazar et al., 2012	A survey on the filter-based feature selection techniques.	Concentrates on filter-based techniques in cancer microarray data.
Chandrashekar and Sahin, 2014; Mohamed et al., 2016	The work concentrates on various feature selection methods in microarray data.	In general, focus on the feature selection methods did not categorize as supervised, unsupervised, or semi-supervised.
Almugren and Alshamlan, 2019	A survey on the hybrid-based gene selection techniques.	Concentrates only on hybrid approach based gene selection methods.
Current Survey	Our survey on the existing literature focuses on the works mentioned above, categorizing into Supervised, Unsupervised, and Semi-Supervised Learning. Also, it discusses the performance of the existing gene selection methods.