第一个code:
data one;
do i = 1 to 4;
output;
end;
run;
data two;
set one;
do c= 1 to 4;
do b= 1 to 4;
end;
end;
run;
第二个 code:
data two;
do i=1 to 4;
output;
do c= 1 to 4;
do b= 1 to 4;
end;
end;end;
run;
为何第一个程序的结果是
i c b
1 5 5
2 5 5
3 5 5
4 5 5
而第二个程序生成的dataset是
i c b
1 . .
2 5 5
3 5 5
4 5 5
第一个observation的c和b是missing
有大神来解释下咩~