1. Data Manipulation: https://www.dropbox.com/scl/fi/flpdfpaiaw40znekwkdnv/data_manipulation.Rmd?rlkey=finfuwezj0fih2nq5t6ysxqit&dl=0
2. Join operation: https://www.dropbox.com/scl/fi/qvjub9vasg0vriud74yut/join_operations.Rmd?rlkey=81txma7afoxg4194sgmou6it2&dl=0