來自http://bbs.pinggu.org/thread-4994985-1-1.html
方法1，first.variable
data test1;
set sashelp.class;
proc sort;
by sex height;
run;
data test2;
set test1;
by sex;
if first.sex then rank_h1 = 0;
rank_h1 + 1 ;
drop age weight;
run;
方法2，proc rank
data test1;
set sashelp.class;
proc sort;
by sex height;
run;
proc rank data=test1 out=test3 (drop=age weight) ;
var height;
by sex;
ranks Mingci;
run;