Worked on enhancing the reliability and correctness of the RaGroupby function in the apache/systemds repository, focusing on data engineering and algorithm implementation using Java and DML. Addressed a runtime error that occurred when processing groups with varying row counts by introducing matrix padding in the permutation-matrix path, ensuring robust handling of heterogeneous group structures. Developed targeted tests to validate the fix and prevent future regressions, thereby improving the stability of data processing workflows. The work emphasized thorough testing and careful attention to edge cases, resulting in a more dependable RaGroupby function for diverse production datasets with complex groupings.