My data set has "subject", "Visit", "Adverse_Event_Start", and "Adverse_Ever_End". I need to create a new column "Advse_Event_Present" based on "Subjec", "Visit", ""Adverse_Event_Start", and "Adverse_Ever_End". In "Adverse_Event_Start" column: "1" means "adverse event started" In "Adverse_Event_End" column: "1" means "adverse event ended" The zero values in both columns are not informative. The "Adverse_Event_Present" are created as following: If Adverse_Event_Start= 1 and Adverse_Event_End=0, the "Adverse_Event_Present" is 1. If Adverse_Event_Start= 0 and Adverse_Event_End=1, the "Adverse_Event_Present" is 0. If Adverse_Event_Start= 1 and Adverse_Event_End=1, the "Adverse_Event_Present" is 1. If Adverse_Event_Start= 0 and Adverse_Event_End=0, the "Adverse_Event_Present" can be "0" or "1" based on previous visit (s) for each subject. For example, for subject= A, Visit=3, the previous visit for the same subject (subject= A, Visit=2) has Adverse_Event_Start=1 and Adverse_Event_End =0, therefore Adverse_Event_Present (for subject= A, Visit=3) should be 1. Below, I fill out the true values for “Adverse_Event_Present” if the program works properly. Any help will be greatly appreciated. Subject Visit Adverse_Event_Start Adverse_Event_End Adverse_Event_Present A 1 0 0 0 A 2 1 0 1 A 3 0 0 1 A 4 0 1 0 A 5 0 0 0 B 1 0 0 0 B 2 1 0 1 B 3 0 0 1 B 4 0 1 0 C 1 1 0 1 C 2 0 0 1 C 3 0 0 1 C 4 0 0 1 D 1 1 1 1 D 2 0 0 0 D 3 0 0 0
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