how do i get unique value from multiple variables into a macro-variable within one data step

[tri_h]

data ex1;
input var1 $ var2 $ var3 $;
cards;
%a b f
b %c d
%g f i
;
run;

what i want is MACRvar=%a|%c|%g, i know the transpose+sort nodupkey could achieve this, how to achieve this with a data step like, data _null_; set ex1... i might thought take use of retain, array...

thanks for your helping.

thanks for helping

[mkeintz]

Declare your new variable (call it mv) as a character variable with a length you know is sufficient.  Then:

data ex1;
input var1 $ var2 $ var3 $;
cards;
%a b f
b %c d
%g f i
run;

data _null_;
  set ex1 end=end_of_ex;
  length mv $24;
  retain mv ;
  if var1=:'%' then mv=catx('|',mv,var1);
  if var2=:'%' then mv=catx('|',mv,var2);
  if var3=:'%' then mv=catx('|',mv,var3);
  if end_of_ex;
  call symput('mvar',mv);
run;

%put %superq(mvar);

I leave it to you to construct the array and corresponding loop.  Just note that the "=:" comparison operator is a convenient way to find values starting with a % sign.

Note I used the %superq function in the %put statement, because otherwise I would have to use the macrovar &mvar (instead of mvar in the superq function).  This would cause the macro interpreter to attempt to resolve the %a%c%g and generate messages like "WARNING: Apparent invocation of macro A not resolved."

There may be a macro function such that I could use

  %put %somefunction(&mvar)

without messages generated, but I am unaware of it.

[tri_h]

Sorry, The sample data isn't typical enough, think about:
data ex1;
input var1 $ var2 $ var3 $;
cards;
%a b f
b %c d
%g f %c
run;
there's a repeat ‘%c’, and i want to store it once...

[mkeintz]

While we're at it, what order do you want to concatenate the desired values?  Order of appearance?  Alphabetical?

[tri_h]

Order of appearance would be better, i had tried an index function before the catx like:
if index(mv, arrayVARs)=0 then mv=catx('|', mv, arrayVARs), but it still add '%c' tiwce.

[mkeintz · Accepted solution]

To avoid duplicates, compare the candidate word with the current set of concatenated values using the FINDW function, which returns a 0 if the candidate is not found as a "word" in the concatenation.  "word" here means strings separated by '|':

data ex1;
input var1 $ var2 $ var3 $;
cards;
%a b f
b %c d
%g f %c
run;

data _null_;
  set ex1 end=end_of_ex;
  length mv $24;
  retain mv ;
  if var1=:'%' and findw(mv,trim(var1),'|')=0 then mv=catx('|',mv,var1);
  if var2=:'%' and findw(mv,trim(var2),'|')=0 then mv=catx('|',mv,var2);
  if var3=:'%' and findw(mv,trim(var3),'|')=0 then mv=catx('|',mv,var3);
  if end_of_ex;
  call symput('mvar',mv);
run;

%put %superq(mvar);

Now it's getting busy enough that you'll want to use an array of var1 & var2 & var3, and program a loop.  Note the 2nd argument of the findw function is not var1, but trim(var1) - otherwise any trailing blanks in var1 will be included in the search for a matching string in the MV variable.