Basic help regarding MACROS

[sarav1981]

Hi all,

I am a rookie programmer in SAS. I was trying to learn SAS Macros and I got myself into a real mess in a basic step. I need to store a variable list to a macro variable and then export the variable list in another variable.

I have a data set flights.diabetes which has 20 records in a character variable 'ID'. I am trying to store the entire 20 records into 'varlist'. Then I would like to create a new dataset 'new' and would like to transfer all the 20 records to a new variable 'wt' in the new dataset.

I tried the following code:

data _null_;
set flights.diabetes;
allid = left(id);
call symput('varlist', allid);
run;

%put &varlist;

data new;
wt = &varlist;
run;

All I get in 'wt' is the last value of ID. What should I do to get the entire list of values. Should I try to use arrays to store the entire list?

It would be great if you guys can help me on this as I presume simple MACRO concept.

Thanks,
Sarav

 

[klaz2002]

The reason you get the last record is you are overwriting your macro var with each new observation (record)that the data step goes through. Remember that a data step is an implicit loop. Also, the call symput function is not executed until the 'run' statement is hit.

You need to generate a list of id's and insert it into a string. Then, at the last record insert that string into a macro var. You don't need to call the 'call symout' function at every observation. Here is an example of what I describe.

data _null_;
  set flights.diabetes end =last;
  retain z m;
  length allid m $500;
  z= x;
  if _n_ eq 1 then
    allid =  trim(z);
  else 
    allid = trim(m) ||' '||trim(z);
  m = allid;
  if last then
    call symput('varlist',allid);
run;

I hope that this helps you.
Klaz

 

[sarav1981]

Hi Klaz2002,

Thanks a lot for your help. Now I see the logic clearly.

Sarav