Bayesian Cluster Validity Index R package BayesCVI version 1.0.2 Algorithms for computing and generating plots with and without error bars for Bayesian cluster validity index (BCVI) (O. Preedasawakul, and N. Wiroonsri, A Bayesian Cluster Validity Index, Computational Statistics & Data Analysis, 202, 108053, 2025. <doi:10.1016/j.csda.2024.108053>) based on several underlying cluster validity indexes (CVIs) including Calinski-Harabasz, Chou-Su-Lai, Davies-Bouldin, Dunn, Pakhira-Bandyopadhyay-Maulik, Point biserial correlation, the score function, Starczewski, and Wiroonsri indices for hard clustering, and Correlation Cluster Validity, the generalized C, HF, KWON, KWON2, Modified Pakhira-Bandyopadhyay-Maulik, Pakhira-Bandyopadhyay-Maulik, Tang, Wiroonsri-Preedasawakul, Wu-Li, and Xie-Beni indices for soft clustering. The package is compatible with K-means, fuzzy C means, EM clustering, and hierarchical clustering (single, average, and complete linkage). Though BCVI is compatible with any underlying existing CVIs, we recommend users to use either WI or WP as the underlying CVI. Software Depends: R (>= 2.10) Imports: e1071, mclust, ggplot2, UniversalCVI Onthada Preedasawakul <o.preedasawakul@gmail.com> Comprehensive R Archive Network (CRAN) Nathakhun Wiroonsri [aut] (ORCID: <https://orcid.org/0000-0003-2167-9641>), Onthada Preedasawakul [cre, aut] (ORCID: <https://orcid.org/0000-0002-4186-3158>) GPL (>= 3) 2025-07-09 application/tgz https://CRAN.R-project.org/package=BayesCVI doi:10.32614/CRAN.package.BayesCVI