Displaying 1 result from an estimated 1 matches for "last_visit_date".
2011 Aug 24
3
Creating new variable with maximum visit date by group_id
...am encoutering the following problem: I have a dataset with a 'unique_id' and different 'visit_date' (formatted as.Date, "%d/%m/%Y") per unique_id. I would like to create a new variable with the most recent date of visit per unique_id as shown below.
unique_id visit_date last_visit_date
1 01/06/2010 01/06/2011
1 01/01/2011 01/06/2011
1 01/06/2011 01/06/2011
2 01/01/2009 01/07/2011
2 01/06/2009 01/07/2011
2 01/06/2010 01/07/2011
2 01/01/2011 01/07/2011
2 01/07/2011 01/07/2011
3 01/01/2008 01/01/2008
4 01/01/2009 01/01/2010
4 01/01/2010 01/01/2010...