output statement

[taylormccormick]

I'm trying to understand the output statement and the PDV.  

If I don't include the output statement after each assignment, the output data looks like this...

Code:

DATA WORK.HRLeaders2;

LENGTH Player $ 7;

Season=2016; Player='Trumbo'; HR=47;

Season=2017; Player='Stanton'; HR=59;

Season=2018; Player='Davis'; HR=48;

RUN;

Output:

Obs Player Season HR1

Davis

2018

48

If I include after each statement it looks like this...

Code:

DATA WORK.HRLeaders2;

LENGTH Player $ 7;

Season=2016; Player='Trumbo'; HR=47;OUTPUT;

Season=2017; Player='Stanton'; HR=59;OUTPUT;

Season=2018; Player='Davis'; HR=48;OUTPUT;

RUN;

Output:

Obs Player Season HR123

Trumbo	2016	47
Stanton	2017	59
Davis	2018	48

If I include after first statement only, it looks like this...

Code:

DATA WORK.HRLeaders2;

LENGTH Player $ 7;

Season=2016; Player='Trumbo'; HR=47; OUTPUT;

Season=2017; Player='Stanton'; HR=59;

Season=2018; Player='Davis'; HR=48;

RUN;

Output:

Obs Player Season HR1

Trumbo

2016

47

Why wouldn't it output both the first and last observation in the output data set?  And are the other two observations then "lost" (created temporarily but gone because I didn't output them to a dataset)?

Thanks!  I know it's a simple question, just trying to understand.

[Reeza]

Once you have an explicit OUTPUT statement it overrides the default implicit OUTPUT statement which is at the RUN line.

So in the first set of code you have a single implicit output at the end, at the RUN. There is no loop as each line was overwritten with the previous value so only the last value is printed.

In the third example, your explicit OUTPUT statement overrides the implicit OUTPUT. It is only present once and dumps the current values. Since there is no other OUTPUT statement no other records are written to the data set.

[CurtisMackWSIPP]

Rezza is of course correct.

Remember, the data step is an implied loop through every record in the input datasets.  If while in a DATA step loop it executes a SET, MERGE, UPDATE, MODIFY, or INPUT statement, it reads the next record into the PDV. If there is another records after the one read, it remembers that.  It then progress through the rest of the data step code.  If it finds an OUTPUT statement, it writes out the current record and remembers it has been written.  When it hits a "run" statement (or another DATA or PROC statement if you forget the RUN), and it hasn't already been output, it outputs the record.  If there are still more records from the last input dataset, it goes back to the top of the code and starts over.  You can have more than one OUTPUT and it will output the record every time it sees one.