先看一看lstar 里面都有什么变量和数据
use
proc contents； ＝data＝lstar； run；
proc print; data=lstar; run;

有没有 i， sample, 有几个 ＿n，＿s， ＿d 。。。

sample i  都有

t seems that the if condition: _s[k]< 1 is failed.
It also seems the array variabes _k[10] and _d[10] are not initialized, which means that there is no value.

you need to check the initial value of the array variables _s[10] and _d[10]
To do this by issue a few put _all_ statement at different lines.

such as

data shifts_drifts;
  set lstar;
  by sample;
  array _n[10] _temporary_ (1 2 3 4 5 6 7 8 9 10);
  array _s[10] _temporary_;  array _d[10] _temporary_;
put ' _A_ ' put _all_;
  if first.sample then call missing(of _s[*] _d[*]);
put ' _B_ ' put _all_;
  do k =1 to dim(_n);
put ' _C_ ' put _all_;
    if _s[k] <1 then if (sum1 ge (2.01+0.01*(_n[k]-1))) then do;
put ' _D_ ' put _all_;
      _s[k] =1; n =_n[k]; cat ='shifts';
      output shifts_drifts;
keep sample n i cat;
    end;
    if _d[k] <1 then if (sum2 ge (2.01+0.01*(_n[k]-1))) then do;
      _d[k] =1; n =_n[k]; cat ='drifts';
      output shifts_drifts;
keep sample n i cat;
    end;
  end;
run;

array _n[11] _temporary_ (1 2  3 4 5 6 7 8 9 10 11);
把括号里的数改成从1到1000，怎么改呢，请您继续执教

not sure, try 1:1000 or 1-1000