How to use SAS macro with %DO and %IF

Question

When I ran a macro, the PassengerID_Class had a null value.

I think there is a problem with the sentence below.

%if PassengerID >= &&P&i and PassengerID < &&P&k %then PassengerID_Class = &i. ;

PassengerID is a column containing values from 1 to 891 .

P1 , P2 ,..., Pi are the quantiles.

Below is my code.

%macro do_loop;

DATA _NULL_;
SET PERCENTILES100_Transpose;
call symput("P"||left(_n_),Column1);
RUN;  

Data Groups100;
Set sample;

%do i=2 %to 99;
%Let k = %eval(&i.+1);
%if PassengerID >= &&P&i and PassengerID < &&P&k %then PassengerID_Class = &i. ;
%end;

%mend;

%do_loop;

Answer 1

You cannot test the value of dataset variable with a macro expression. Just use the macro to generate a normal IF statement, the same as you are using the macro to generate the DATA and other SAS statements.

if &&P&i <= PassengerID < &&P&k then PassengerID_Class = &i. ;

But why use macro code at all? Just read the cutoff values into a temporary array.

data Groups100;
  set sample;
  array p[100] _temporary_;
  if _n_=1 then do index=1 by 1 until(eof);
     set PERCENTILES100_Transpose(keep=column1) end=eof;
     p[index]=column1;
  end;
  PassengerID_Class=0;
  do index=2 to 99 until(PassengerID_Class>0);
    if p[index] <= PassengerID < p[index+1] then PassengerID_Class = index ;
  end;
  drop index column1 ;
run;

Note that using the data directly will also avoid loss of precision caused by converting the numbers into text strings to store macro variables.