如何根据逐个组内的观察(行)数放弃观察？

Question

在Stata,我可以这样做:

bysort group_var: drop if _n > 6

只保留前六个观察各组内,通过指定group_var.我如何在SAS中执行此操作？

我试过了:

proc sort data=indata out=sorted_data;
    by group_var;
run;

data outdata;
    set sorted_data;
    by group_var;
    if (_n_ > 6) then delete;
run;

但这会删除整个数据集中除了前六个观测值之外的所有观测值(总共只留下六个观测值).

Answer 1

您需要按组计算每个记录.

data outdata;
   set sorted_data;
   by group_var;
   retain count;

   if first.group_var then
      count = 0;

   count = count + 1;
   if count > 6 then delete;

   drop count;
run;