Item 51
The SAS data set WORK.TEMP is indexed on the variable Id:
Id Amount
-- ------
P 52
P 45
A 13
A 56
R 34
R 12
R 78
The following SAS program is submitted:
proc print data=WORK.TEMP;
[_insert_BY_statement_]
run;
Which BY statement completes the program, creates a listing report that is grouped
by Id, and completes without errors?
A. by Id;
B. by Id grouped;
C. by Id descending;
D. by descending Id;
答案是A,解释中说“SAS执行时,会按已索引的顺序(APR)的顺序来分组输出观测”。
其实,还是不明白,为什么呢?? 有没有哪位高手详细解释一下??
多谢多谢!![em49]