Function that uses a string as argument

[yellowyellowred]

Sorry for the confusing title. Here is what I mean:  
I have a dataset

before_group_3	after_group_3	before_group_4	after_group_4	before	after
3	4	1	2	before_group_3	after_group_3
5	6	3	4	before_group_4	after_group_4
7	7	1	2	before_group_3	after_group_3

I want to add another column:

before_group_3	after_group_3	before_group_4	after_group_4	before	after	before_eval	after_eval
3	4	1	2	before_group_3	after_group_3	3	4
5	6	10	11	before_group_4	after_group_4	10	11
7	7	1	2	before_group_3	after_group_3	3	4

I think that I could do in a datastep:

if before = "before_group_3" then before_eval = before_group_3;

if before = "before_group_4" then before_eval = before_group_4;

so I want a function that does this:
before_eval = FUNCTION(before)  
  
I have a lot more groups, e.g. group_99, so that's why I want a function like this

[Ksharp · Accepted solution]

data have;
infile cards expandtabs;
input before_group_3	after_group_3	before_group_4	after_group_4	before :$20.	after  :$20.;
cards;
3	4	1	2	before_group_3	after_group_3
5	6	3	4	before_group_4	after_group_4
7	7	1	2	before_group_3	after_group_3
;

data want;
 set have;
 before_eval=vvaluex(before);
 after_eval=vvaluex(after);
run;

[yellowyellowred]

Thanks! Is there a function that returns a numeric instead?

[jklaverstijn]

VVALUE(X) is designed to return a character. You can wrap the call to VVALUEX in a call to INPUT:

data want;
 set have;
 before_eval=input(vvaluex(before), best.);
 after_eval=input(vvaluex(after), best.);
run;

- Jan

[Tom]

---

@yellowyellowred wrote:

Thanks! Is there a function that returns a numeric instead?

---

Not as simply.

You could convert the string back to a number.

number = input( vvaluex( variable_with_name ) , 32. );

You could do some tricks so you could index into an array.

array numbers var1 var2 var3 ;
array names $32 [3] _temporary_ ('var1','var2','var3');
number = numbers[ whichc( variable_with_name, of names[*]) ] ;

 Or 

array numbers var1 var2 var3 ;
number = numbers[ findw('var1 var2 var3', variable_with_name,' ','e') ] ;

[Kurt_Bremser]

before_eval = input(scan(before,-1,"_"),best.);

to extract the numeric value from the string.