topic Re: Help to understand code in SAS Enterprise Guide

Help to understand code

woo — Wed, 20 Jan 2016 19:39:05 GMT

Hello friends, please help me to understand this code, this is not my code, its existing code

I am testing code where one dataset "test" resolving with 3 observation

date file_name

20Jan16 test_file_20160120.txt

19Jan16 test_file_20160119.txt

18Jan16 test_file_20160118.txt

Now after this dataset (test) created, below code is running and its giving only 1 observation, i really don't know why it is resolving to one but i am expecting it should has 3 observation

%macro test (x_date);

%let store_x_date="null";

data test_2;

retain stop_ind;
if _N_ = 1 then stop_ind = 0;
set test;
by DESCENDING DATE;
if last.DATE = 1 then do;
if stop_ind = 0 then do;
output;
Author_DATE = put(DATE, date.);
call symput("&x_date.",Author_DATE);
end;
stop_ind = 1;
end;
if stop_ind = 0 then output;
run;

%mend;

%test (store_x_date);

Thank you

Re: Help to understand code

Reeza — Wed, 20 Jan 2016 20:03:10 GMT

This is where formatting your code helps. Note that there's an output statement nested in an IF condition and a second one in the last statement. The goal seems to be to create a macro variable.

%macro test (x_date);

%let store_x_date="null";

  data test_2;
  retain stop_ind;
  
  if _N_ = 1 then stop_ind = 0;

  set test;
  by DESCENDING DATE;

  if last.DATE = 1 then do;
        if stop_ind = 0 then do;
              output;
              Author_DATE = put(DATE, date.);
              call symput("&x_date.",Author_DATE);
        end;
   stop_ind = 1;
   end;

   if stop_ind = 0 then output;
   run;
%mend;

%test (store_x_date);

Re: Help to understand code

Astounding — Wed, 20 Jan 2016 20:14:05 GMT

Some contributing factors:

Since the DATA step contains an OUTPUT statement, you will only output an observation when an OUTPUT statement executes.
All OUTPUT statements depend on having STOP_IND=0
For this particular set of 3 observations, the 1st observation will output and then set STOP_IND=1
For the 2nd and 2rd observations, STOP_IND=1, so nothing gets output

I hope this is enough ... there's really no substitute for understanding what the statements do.

Re: Help to understand code

woo — Wed, 20 Jan 2016 21:00:37 GMT

Thanks a lot Astouning and Reeza, appreciate your input,