Question

我正在尝试根据每个特定主题的事件的最早实例来检索SAS数据集的子集。这是一个示例数据集：

subject    date
001        12/22/2009
001        01/14/2016
001        03/20/2014
002        02/12/2007
002        01/23/2015

我只想要以下内容：

subject    date
001        12/22/2009
002        02/12/2007

Answer 1

与first.一起使用副处理：

/* sort into order */
proc sort data=have ;
  by subject date ;
run ;

/* Take 1st record per subject (i.e. earliest date) */
data want ;
  set have ;
  by subject ;
  if first.subject ;
run ;

Answer 2

通过proc sql可以如下所示

 proc sql;
 create table want as
 select * from have
 group by subject
 having date=min(date);

或者您可以使用proc手段

   proc means data=have  nway;
   class subject;
   var date;
  output out=want(keep =id date) min(date) =date;
  run;

按日期对每个主题的子集SAS数据集进行分组

2 个答案: