data wide_arrays (drop=Actual i Date);
  set PrdSummary;
  where year(Date)=1997;
  by Product;
  array months {12} Act_Jan Act_Feb Act_Mar Act_Apr Act_May Act_Jun
                    Act_Jul Act_Aug Act_Sep Act_Oct Act_Nov Act_Dec;
  retain Act_Jan Act_Feb Act_Mar Act_Apr Act_May Act_Jun
         Act_Jul Act_Aug Act_Sep Act_Oct Act_Nov Act_Dec;
  format Act_Jan Act_Feb Act_Mar Act_Apr Act_May Act_Jun
         Act_Jul Act_Aug Act_Sep Act_Oct Act_Nov Act_Dec dollar12.2;
  if first.Product then do i=1 to 12;
    months{i}=0;
  end;
  months{month(Date)}+Actual;
  if last.Product;
run;
proc print data=wide_arrays;
  id Product;
  title1 "Rotated results for a single year";
run;