How to get the frequency of combinations of values

[NewUsrStat]

Hi guys, 

suppose to have the following table: 

data DB;
input ID :$20. Resp1 :$20. Resp2 :$20. Resp3 :$20.;
cards;
1 a b .
2 a c .
3 d . .
4 a b f
5 a b .
....
;

Is there a way to get the number of all combinations? 

Desired output: 

Combination	Freq
ab	2
ac	1
d	1
abf	1
......	...

Thank you in advance

[Astounding]

The easy way to count observations in a SAS data set is PROC FREQ:

proc freq data=DB;
tables resp1 * resp2 * resp3 /
list missing;
run;

[Ksharp · Accepted solution]

I love this kind of question.

EDITED

data DB;
input ID :$20. Resp1 :$20. Resp2 :$20. Resp3 :$20.;
cards;
1 a b .
2 a c .
3 d . .
4 a b f
5 a b .
;
data temp;
 set db;
 array r{3} $ Resp1-Resp3;
 call sortc(of r{*});
 do n=1 to dim(r);
   if missing(r{n}) then r{n}='09'x;
 end;

 array x{3};
 length combination $ 80;
 k=-1;
 do i=1 to 2**dim(x);
   rc=graycode(k,of x{*});
   call missing(combination);
   do j=1 to dim(x);
    if x{j}=1 then combination=cats(combination,r{j});
   end;
   if not findc(combination,'09'x) and not missing(combination) then output; 
 end;
 keep combination;
run;
proc freq data=temp noprint;
table combination/out=want ;
run;

[ballardw]

A question that might become of interest would be  is there a difference in the "combination"

1 a b .
2 a . b