An empirical study of identical function clones in CRAN

Code clone analysis is a very active subject of study, and research on inter-project code clones is starting to emerge. In the context of software package repositories specifically, developers are confronted with the choice between depending on code implemented in other packages, or cloning this code in their own package. This article presents an empirical study of identical function clones in the CRAN package archive network, in order to understand the extent of this practice in the R community. Depending on too many packages may hamper maintainability as unexpected conflicts may arise during package updates. Duplicating functions from other packages may reduce maintainability since bug fixes or code changes are not propagated automatically to its clones. We study how the characteristics of cloned functions in CRAN snapshots evolve over time, and classify these clones depending on what has prevented package developers to rely on dependencies instead.