sort Stkcd SHLst_id
by Stkcd : egen order1=rank( SHLst_id )
xtset Stkcd order1
tab order1  //i=max(order1), j=max(order)-1




qui forv j= 1/27 {
forv i=1/11 {
by Stkcd: gen cd`j'`i'=stkcd_`j'[_n-1+`i'] if order1==1
}
}


最后运行结果报错：
variable cd111 already defined


求大佬们帮忙看看