[R] How to avoid two for loops?

HI, I have the following large data set: the sample is as the following: Country Product Brand Year_Month DisplaySize OperationSystem AE 1 20201204 1 1 AE 5 20201204 1 1

[R] help on improving the efficiency of the codes

HI, I have the following large data set: the sample is as the following: Country Product Brand Year_Month DisplaySize OperationSystem AE 1 20201204 1 1 AE 5 20201204 1 1