假设我有这个输入:
ID date_1 date_2 str
1 1 2010-07-04 2008-01-20 A
2 2 2015-07-01 2011-08-31 C
3 3 2015-03-06 2013-01-18 D
4 4 2013-01-10 2011-08-30 D
5 5 2014-06-04 2011-09-18 B
6 5 2014-06-04 2011-09-18 B
7 6 2012-11-22 2011-09-28 C
8 7 2014-06-17 2013-08-04 A
10 7 2014-06-17 2013-08-04 B
11 7 2014-06-17 2013-08-04 B
我想str通过group变量逐步连接列的值ID,如以下输出所示:
ID date_1 date_2 str
1 1 2010-07-04 2008-01-20 A
2 2 2015-07-01 2011-08-31 C
3 3 2015-03-06 2013-01-18 D
4 …