topic Re: Combinations and Permutations in SAS Programming

Combinations and Permutations

sdixit — Thu, 14 Jul 2016 18:32:01 GMT

Hi All,

I have a numeric value or string like

1-4
5
5+
5-
6
6+
6-
7
7+
7-
8
9
9+
9-
10

And I would like to create a string concatinated from above using combination and permutition of any combination of above numbers.

and then I need to check in my data if the variable has any of the combination of the string defined above.

Possible Unique Combinations	# in String	Example
15	1	1-4
105	2	1-4, 5
455	3	1-4, 5, 5+
1365	4	1-4,5, 5+, 5-
3003	5	1-4, 5, 5+, 5-, 6
5005	6	1-4, 5, 5+, 5-, 6, 6+
6435	7	1-4, 5, 5+, 5-, 6, 6+ 6-
6435	8	1-4, 5, 5+, 5-, 6, 6+, 6-, 7
5005	9	1-4, 5, 5+, 5-, 6, 6+, 6-, 7, 7+
3003	10	1-4, 5, 5+, 5-, 6, 6+, 6-, 7, 7+, 7-
1365	11	1-4, 5, 5+, 5-, 6, 6+, 6-, 7, 7+, 7-, 8
455	12	1-4, 5, 5+, 5-, 6, 6+, 6-, 7, 7+, 7-, 8, 9
105	13	1-4, 5, 5+, 5-, 6, 6+, 6-, 7, 7+, 7-, 8, 9, 9+
15	14	1-4, 5, 5+, 5-, 6, 6+, 6-, 7, 7+, 7-, 8, 9, 9+, 9-
1	15	1-4, 5, 5+, 5-, 6, 6+, 6-, 7, 7+, 7-, 8, 9, 9+, 9-, 10

Can anyone help?

Re: Combinations and Permutations

PGStats — Thu, 14 Jul 2016 18:45:48 GMT

Since every combination is allowed, wouldn't it be more efficient to check that all elements of the variable are among the allowed 15 substrings?

Re: Combinations and Permutations

Astounding — Thu, 14 Jul 2016 19:05:48 GMT

Check your data? What data? What are you trying to check?

It's not that difficult to create 32K combinations (at least I assume you want combinations, but not permutations ... combinations would match with the column in your chart about Possible Unique Combinations). But what do you want to do once you have them? That part is very far from being clear.

Re: Combinations and Permutations

sdixit — Thu, 14 Jul 2016 19:16:11 GMT

I want to check in if my data matches with any combination of the 15 strings

Re: Combinations and Permutations

Astounding — Thu, 14 Jul 2016 19:19:03 GMT

What variable (or variables) exist in your data?

Give us 3 examples of a match and 3 examples of a mismatch.

Re: Combinations and Permutations

sdixit — Thu, 14 Jul 2016 19:23:03 GMT

Sure,

Lets Take in Example :

consider "1-4, 5, 5+, 5-, 6, 6+ 6-" as a string created from the combination of any number from the string mentioned above.

And My data also has the same string ""1-4, 5, 5+, 5-, 6, 6+ 6-" for a record

and other raw has "8,9 ,10 " which does not matches from the above string.

Re: Combinations and Permutations

Astounding — Thu, 14 Jul 2016 19:27:29 GMT

So your data set contains a long string as a single variable. If your data contains this, it is a match:

1-4, 5, 5+, 5-, 6, 6+, 6-

What if your data contains this instead, is it still a match:

6-, 1-4, 5, 5+, 5-, 6, 6+

Re: Combinations and Permutations

sdixit — Thu, 14 Jul 2016 19:32:06 GMT

yes , This should be a match, Thats why I asked to have a logic which will create any conbination and any permutation of the string.

Re: Combinations and Permutations

Astounding — Thu, 14 Jul 2016 19:37:31 GMT

Then I agree with PGStats. You don't need to create all combinations and permutations. You just need to check each element of your data against a list of 15 possibilities. There are many ways to go about this. No matter which way you choose, you need to be able to move through your data elements:

match='Y';

length nextword $ 3;

if long_string > ' ' then do _n_=1 to countw(long_string, ',');

nextword = scan(long_string, _n_, ',');

* some sort of checking here that might set MATCH to "N" ;

end;

Do you need more of the details on how to check?

Re: Combinations and Permutations

ballardw — Thu, 14 Jul 2016 19:54:09 GMT

Expanding on @Astounding and @PGStats :

data want;
   set have;
   array test (15) $ 3 _temporary_('1-4','5','5+','5-','6','','6+','6-','7','7+','7-','8','9','9+','9-','10');
   length nextword $ 3;
   Match='Yes';
   if not missing(long_string) then do _n_=1 to countw(long_string,', ');
      nextword = scan(long_string,_n_,', '); 
      if whichc(nextword,of test(*)) = 0 then Match='NO';
   end;
   drop nextword;
run;

Could add a If Match='NO' then Leave; to shorten the runtime but likely to be insignificant unless you have a large input set.

Long_string is the name of your string variable you are testing.

Re: Combinations and Permutations

sdixit — Wed, 20 Jul 2016 17:01:20 GMT

Thanks

The requirement has changed a bit.

so now my motive is to create a flag when my variable matches with any number from ('8', '9+',' 9', '9-', '10') string.

So if there is any number present in my variable ABC , it should set the flag = "Y".

My data looks like :

ABC	Flag
5,7,8	Y
9,7,4	Y
8	Y
9	Y
9+	Y
9-	Y
10	Y
5,6	N
3,2	N

You suggestion works if we have 2 number or greater in the string.but if there is only 1 digit then it wont work. Pls suggest for that

Re: Combinations and Permutations

sdixit — Wed, 20 Jul 2016 17:17:17 GMT

data want;

set have;

array lookup(5) $10 _temporary_ ('8' '9+' '9' '9-' '10');

n=countw(abc);

flag='N';

do i=1 to n;

part=strip(scan(abc, i, ","));

if whichc(part, of lookup(*))>0 then flag='Y';

end;

keep abc flag ;run;

This works. Thanks for you help.