Fast Calculation of Feature Contributions in Boosting Trees R package qshap version 1.0 Computes feature-specific R-squared (R2) contributions for boosting tree models using a Shapley-value-based decomposition of the total R-squared in polynomial time. Supports models fitted with 'XGBoost' and 'LightGBM', and provides efficient parallel implementations suitable for large-scale problems. Multiple visualization tools are included for interpreting and communicating feature contributions. The methodology is described in Jiang, Zhang, and Zhang (2025) <doi:10.48550/arXiv.2407.03515>. Software Imports: Rcpp (>= 1.0.14), xgboost (>= 3.1.3.1), parallel, lightgbm, viridisLite, ggplot2, jsonlite, methods, progress LinkingTo: Rcpp, RcppEigen Suggests: shiny Zhongli Jiang <zhongli.jiang.stats@gmail.com> Comprehensive R Archive Network (CRAN) Steven He [aut], Zhongli Jiang [aut, cre], Dabao Zhang [aut] GPL (>= 2) 2026-03-16 application/tgz https://CRAN.R-project.org/package=qshap doi:10.32614/CRAN.package.qshap