creating time intervals 30 days

[lillymaginta]

data a;
  input patientid  start : mmddyy10.  end : mmddyy10. ;
  format   start end  mmddyy10.;
datalines;
1  1/1/2006 4/1/2006
 
2   1/2/2006 12/2/2007;
run;

I have data that contains one row per patient with start and end date. I want to create 30 days interval following the start date until the end date. The output would be : 

1 1/1/2006 31/12006 

1 31/1/2006  3/2/2006 

1 3/2/2006   4/1/2006

2 1/2/2006  2/1/2006

and so on 

[novinosrin · Accepted solution]

data a;
  input patientid  start : mmddyy10.  end : mmddyy10. ;
  format   start end  date9.;
datalines;
1  1/1/2006 4/1/2006
2   1/2/2006 12/2/2007
;
run;


data want;
set a(rename=end=_end);
do while(start<_end);
end=intnx('days',start,30);
output;
start=end;
end;
format start end mmddyy10.;
drop _:;
run;

[lillymaginta]

Thank you! 

[Astounding]

Here's one way to approach the problem.  It's untested code, so you will have to verify whether the results are correct:

data want;

set have;

original_end = end;

do while (end - start > 30);

   end = start + 30;

   output;

   start = end ;

   end = original_end;

end;

output;

drop original_end;

run;

Notice how it's a little harder to read because END is both a SAS statement and a variable name.  If it's within your control, try to avoid that situation.

[Kurt_Bremser]

Please be consistent with your date formatting. I suggest to use the yymmddd10. format, as that is ISO-compliant.

As it is, some of your dates in then output seem to be DMY order, while others are MDY.