Dear All My data set is as follows Var_A Var_B Date 1 120 02JAN2020 1 120 05JAN2020 231 CH 06FEB2020 231 CH 12FEB2020 231 CH 15FEB2020 139 SELF 15JAN2020 139 SELF 19JAN2020 139 SELF 2 3 07JAN2020 139 SELF 2 3 15FEB2020 139 SELF 41 09FEB2020 141 SELF 4g 15MAR2020 141 SELF 4g 21MAR2020 141 SELF5 14MAR2020 I want to create a new variable, VAR_C, and the data should look like: Var_A Var_B Date VAR_C 1 120 02JAN2020 120 1 120 05JAN2020 120 231 CH 06FEB2020 CH 231 CH 12FEB2020 CH 231 CH 15FEB2020 CH 139 SELF 15JAN2020 SELF_MAIN 139 SELF 19JAN2020 SELF_MAIN 139 SELF 2 3 07JAN2020 SELF_SUB 139 SELF 2 3 15FEB2020 SELF_SUB 139 SELF 41 09FEB2020 SELF_SUB 141 SELF 4g 15MAR2020 SELF_SUB 141 SELF 4g 21MAR2020 SELF_SUB 141 SELF5 14MAR2020 SELF_SUB
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