How to merge two varlists

[Moh]

How to merge Alist and Blist to have Clist containing all variables in two mentioned lists?

%let Alist = x1 x2 x3 x4 x5 ;

%let Blist = x4 x5 x6 ;

[Reeza]

%let clist = &alist. &blist.;

[Moh]

Thanks Reeza for your reply.Let me clarify myself. I want to avoid duplicated variables as well.

[FreelanceReinh]

I guess you wrote "merge" and not "concatenate" because you would like your "Clist" to be free of duplicates.

I'm not aware of an easy solution to this task, but a quick search on the web brought up this discussion:

http://stackoverflow.com/questions/33640976/how-do-i-deduplicate-words-in-a-character-variable

The solution provided by user "Chris J" promises to deduplicate the concatenated list suggested by @Reeza, but I haven't tested it.

However, it depends on how you are going to use Clist, whether you really need to have it duplicate free. In DROP or KEEP statements (or dataset options), for example, duplicate variable names do no harm.

[Moh]

many thanks for your reply but i need to avoid duplicated variables in new varlist. 

[data_null__]

Do you need to maintain any particular order of the variable names in the list? Do the variables mentioned in the lists exist, or need to exist, or are they just arbitrary SAS-names?

[Moh]

Hi - 

- order does not matter, although preferable 

- yes variables in the list exist. 

thx

[Astounding]

A few more considerations ...

Does capitalization matter?  If one list contains "name" and the other contains "Name", are those duplicates?

Could duplicates exist within just one of the lists?  For example, is it possible that &alist = name height name?

I know I have seen this problem addressed in a SAS Press book.  Macro Language Magic has a chapter on generating text.  But I would hesitate to just copy a section of copyrighted material here.

Good luck.

[Moh]

Hi - thanks for your reply.

- Capitalization does not matter.

- duplication in one list is not possible.

Thanks

[Astounding · Accepted solution]

Here's an approach ... you would need to apply it to both ALIST and BLIST.  You would clearly need to encapsulate this inside a macro definition as well since it uses %DO and %IF.

%let clist=%upcase(&alist);

%do i=1 %to %sysfunc(countw(&blist));

   %let onevar = %upcase(%scan(&blist, &i));

   %if %index(%str( &clist ), %str( &onevar ))=0 %then %let clist = &clist &onevar;

%end;

[Moh]

Astounding , Thanks soooooo much!!!!! It works very well .....