generate id for each group with repeated and missing observations
问题 I have a dataset with individuals observed over several weeks. Some individuals have no observations in some weeks, and some have several observations during the same week. I need to create a weekly ID(id_week in the code) that would be individual-specific. If an individual have two or more observations in one week, id_week should be the same for both observations. If an individual have no observations in a given week, the observation in a next week should be consuequent from the last