Do while ?

[Ivy]

Dear friends, 

I would like to create the "combo2 and old" at the highlight below based on the conditions, and comparing the variables at end of the condition or 1st record dose not apply the condition. I am wondering what is wrong with the "do while" statement.

   Thank you very much!

data t;
input dt date9. name $ ;
format dt mmddyy10.;
datalines;
09SEP2015 a
29SEP2015 b
30SEP2015 a
06OCT2015 b
02NOV2015 c
16NOV2015 a
23NOV2015 c
30NOV2015 a
;
run;

data t1;
set t;

format dt1 mmddyy10. ;
retain dt1 combo1 combo2;

length combo1 combo2  $20. ; 

if name = 'c' and dt ='02NOV2015'd then do;
combo1 = 'a+b';
combo2 = 'c';
dt1 = dt;
end;

else  do;

         do while (.< dt1 < dt < dt1 + 20);
               if findw(combo2, strip(name)) = 0 then combo2 = cats(combo2,"+", strip(name));
        end;

      do i = 1 to countc(combo1, "+") + 1 ;
         if findw(combo2, strip(scan(combo1, i, "+"))) > 0 then old = 1;
      else old = 0;
      end;

end;

run;

dt	name	Combo1	combo2	old	Dt1
9/9/2015	a
9/29/2015	b
9/30/2015	a
10/6/2015	b	a+b
11/2/2015	c				11/2/2015
11/16/2015	a		c+a	1	11/2/2015
11/23/2015	c				11/2/2015
11/30/2015	a				11/2/2015

[PeterClemmensen]

I'm not really following the logic here. Can you elaborate?

[Ivy]

When I see name "c", I want to evaluate all the names during the conditional date (20 days period after seeing name "C"), then at the last record of the conditions to comparing with "a+b".

[Astounding]

Start here and see if this clears it up.  This statement causes a problem:

combo2 = 'c';

It defines COMBO2 as being 1 character long, so there isn't room to add more characters to the end of it.  Try adding this statement beforehand:

length combo2 $ 10;

[Ivy]

The problem is " DO While" do not run. 😞

[Astounding]

Good thing it didn't run.  If it did run, it would still be running for as long as you keep your computer turned on.  The logic of the DO WHILE loop will never change your condition from being true to being false, so it will run forever. 

Perhaps you should explain what it is you would like the DO WHILE loop to accomplish, and we can modify the program accordingly.

[Ivy]

Thanks. My goal is below, actually, the program is running never stops.

When I see name "c", I want to evaluate all the names during the conditional date (20 days period after seeing name "C"), then at the last record of the conditions to comparing with "a+b".

[ballardw]

---

@Ivy wrote:

Dear friends, 

I would like to create the "combo2 and old" at the highlight below based on the conditions, and comparing the variables at end of the condition or 1st record dose not apply the condition. I am wondering what is wrong with the "do while" statement.

   Thank you very much!

data t;
input dt date9. name $ ;
format dt mmddyy10.;
datalines;
09SEP2015 a
29SEP2015 b
30SEP2015 a
06OCT2015 b
02NOV2015 c
16NOV2015 a
23NOV2015 c
30NOV2015 a
;
run;

data t1;
set t;

format dt1 mmddyy10. ;
retain dt1 combo1 combo2;

length combo1 combo2  $20. ; 

if name = 'c' and dt ='02NOV2015'd then do;
combo1 = 'a+b';
combo2 = 'c';
dt1 = dt;
end;

else  do;

         do while (dt1 < dt < dt1 + 20);
               if findw(combo2, strip(name)) = 0 then combo2 = cats(combo2,"+", strip(name));
        end;

      do i = 1 to countc(combo1, "+") + 1 ;
         if findw(combo2, strip(scan(combo1, i, "+"))) > 0 then old = 1;
      else old = 0;
      end;

end;

run;

dt	name	Combo1	combo2	old
9/9/2015	a
9/29/2015	b
9/30/2015	a
10/6/2015	b	a+b
11/2/2015	c		c
11/16/2015	a		c+a	1
11/23/2015	c
11/30/2015	a

---

Since DT1 starts out = DT and never changes  the comparison

(dt1 < dt < dt1 + 20)

is always false. For any value  A<A is false. So the Do While loop never initiates because you have told it not to.

For that Do While loop to have any  use you likely need to be doing something, but I haven't a clue what the need is, to the variable DT1 and your start condition needs to be better defined as well as your rule for how to determine which records need to be processed in general.