* Sample 24667: Load a SAS DATA set into a hash object and create a SAS DATA set from a hash object;
* 원본 : http://support.sas.com/kb/24/667.html;
data a;
input key a b c;
datalines;
1 10 100 1
1 20 200 2
2 10 100 3
3 10 100 4
4 10 100 5
4 20 200 6
;
data _null_;
/* On the first iteration of the DATA step, create a hash table called H */
/* and load it with the values from WORK.A. Define the KEY and DATA */
/* values for H. Note that by default, key values must be unique in a */
/* hash object, so not every record will be loaded into H. (Starting in */
/* SAS 9.2, the MULTIDATA: 'YES' argument tag can be used on the DECLARE */
/* statement to allow multiple records with the same key value in a hash */
/* object.) Also, only those variables defined in DEFINEDATA will be */
/* output to WORK.OUT. Use CALL MISSING to avoid the NOTE in the log that*/
/* the specified variables were uninitialized. An assignment statement */
/* for these variables would work as well. */
if _n_ = 1 then do;
* h hash object 정의;
declare hash h(dataset: "work.a");
* key 값 정의;
h.definekey('key');
* hash object에 생성되는 data 항목 정의;
h.definedata('a','b','c');
* 위에서 생성한 데이터를 로딩하여 hash object 생성;
h.definedone();
call missing(key,a,b,c);
end;
/* Use the OUTPUT method to output the records from the hash object H to */
/* the data set WORK.OUT. */
* SAS 데이터 세트 출력;
rc = h.output(dataset: "work.out");
run;
/* Note, neither KEY nor C will be in WORK.OUT because they were not */
/* defined in the DEFINEDATA method in the step above. */
* 동이한 key 값 중에서 첫번째 값이 출력된다.(확인을 위하여 원본의 c 변수를 관측치 순서로 변경);
proc print data=work.out;
run;
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