Modernization of the TMVA GUI. RVariablePlotter : modular plotting for TMVA

The purpose of this report is to cover the work done during my Summer Student programme at CERN. It focuses on data visualization, which is an interdisciplinary field that deals with the graphical representation of information and data. In particular, this project focuses on the modernization of the TMVA Graphical User Inteface (GUI). Data visualization is crucial for scientific modeling and for communicate information clearly. One of the prerequisite to obtain a satisfactory result, from this perspective, is to allow the toolkit of choice to be modular and not monolithic. In our work we pave the way for such a modularity by implementing a new class, namely RVariablePlotter, which provides tight in- tegration with several ROOT's data structures, such as RDataFrame and RTensor, and allows plotting both feature's distributions and basic performance measurements for classification problems, e.g. ROC Curves, ROC AUC Score. Along with this class, we provide several examples for an easier understanding, which can be further adapted to custom datasets or ROOT's output files. All the code has been submitted as a Pull Request (PR #8723 1) on the official Github repository of the ROOT project.