Date:         Sun, 13 May 2001 14:33:48 -0500
Reply-To:     shiling@math.wayne.edu
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Shiling Zhang <shiling@MATH.WAYNE.EDU>
Organization: Wayne State University
Subject:      Permutations and combinations
Content-Type: text/plain; charset=us-ascii

Here is a general macro solution for the permutation.

1241  %macro perm(n=6,stg='abcdefghijklmnopqrstuvwxyz');
1242
1243       data combos;
1244        array lets(&n) $1 _temporary_;
1245        do i=1 to &n;
1246           lets(i)=substr(&stg,i,1);
1247        end;
1248        * 1st loop;
1249        do _1 = 1 to &n;
1250          %do i = 2 %to &n;
1251            %str(*) &i.th loop;
1252            do _&i=1 to &n;
1253              %let ifst=if;
1254              %do j=1 %to &i-1;
1255                %let ifst=&ifst _&j=_&i;
1256                %if &j+1=&i %then  %let ifst=&ifst then
continue%str(;);
1257                %else  %let ifst=&ifst or;
1258              %end;
1259              &ifst
1260          %end;
1261          %do i=1 %to &n;
1262            %if &i=1 %then %let letter=lets(_&i);
1263            %else  %let letter= &letter || lets(_&i);
1264          %end;
1265           letter=&letter;
1266           output;
1267          %do i = 1 %to &n;
1268            end;
1269          %end;
1270
1271          keep letter;
1272        run ;
1273
1274  %mend;
1275
1276  options mprint;
1277  %perm
1278
MPRINT(PERM):   DATA COMBOS;
MPRINT(PERM):   ARRAY LETS(6) $1 _TEMPORARY_;
MPRINT(PERM):   DO I=1 TO 6;
MPRINT(PERM):   LETS(I)=SUBSTR('abcdefghijklmnopqrstuvwxyz',I,1);
MPRINT(PERM):   END;
MPRINT(PERM):   * 1ST LOOP;
MPRINT(PERM):   DO _1 = 1 TO 6;
MPRINT(PERM):   * 2TH LOOP;
MPRINT(PERM):   DO _2=1 TO 6;
MPRINT(PERM):   IF _1=_2 THEN CONTINUE;
MPRINT(PERM):   * 3TH LOOP;
MPRINT(PERM):   DO _3=1 TO 6;
MPRINT(PERM):   IF _1=_3 OR _2=_3 THEN CONTINUE;
MPRINT(PERM):   * 4TH LOOP;
MPRINT(PERM):   DO _4=1 TO 6;
MPRINT(PERM):   IF _1=_4 OR _2=_4 OR _3=_4 THEN CONTINUE;
MPRINT(PERM):   * 5TH LOOP;
MPRINT(PERM):   DO _5=1 TO 6;
MPRINT(PERM):   IF _1=_5 OR _2=_5 OR _3=_5 OR _4=_5 THEN CONTINUE;
MPRINT(PERM):   * 6TH LOOP;
MPRINT(PERM):   DO _6=1 TO 6;
MPRINT(PERM):   IF _1=_6 OR _2=_6 OR _3=_6 OR _4=_6 OR _5=_6 THEN
CONTINUE;
MPRINT(PERM):   LETTER=LETS(_1) || LETS(_2) || LETS(_3) || LETS(_4) ||
LETS(_5) || LETS(_6);
MPRINT(PERM):   OUTPUT;
MPRINT(PERM):   END;
MPRINT(PERM):   END;
MPRINT(PERM):   END;
MPRINT(PERM):   END;
MPRINT(PERM):   END;
MPRINT(PERM):   END;
MPRINT(PERM):   KEEP LETTER;
MPRINT(PERM):   RUN ;

NOTE: The data set WORK.COMBOS has 720 observations and 1 variables.
NOTE: The DATA statement used 0.22 seconds.


**************************************************************
Hi all,

Requirement: take a series of up to 9 letters and then work out every
permutation and output results to a data set for
later matching to a much larger data set of values.  Code might also
have to
work out combinations too.

How the hell do I code something to work out combinations ?  I can't see
any
functions as such.  Has anyone done anything like that and would you be
willing to share your code ?  I've had a few abortive attempts but I'm
struggling.

Thank you in advance.

Alistair.