SAS macro loop and dummy variable

Question

I just want to make new dummy variable when there is a certain value.

Here is my orignal data example.

ID A1 A2... A10
1  10   1    5
2  20   8   4
...
...

And I would like to add dummy variable when there is a certain value in those attributes. For example, ID 1 subject have "10", a new variable, Add10 would be 1..

ID A1 A2.. A10 Add1..Add4 Add5...Add20

1  10   1.. 5  1  ...0   1  ...    0

2   20  8.. 4  0  ...1   0  ...     1

...

Here is my code..

%MACRO DO_LIST;
%DO I=1 %TO 20;

data aaaa;
set aa33; 
if A1 =i or
A2 =i or
A3 =i or
...
A10 =i then Add&I=I ;
RUN;
%END;  
%MEND DO_LIST;
%DO_LIST;

However, my result have only Add20, which is the last variable.. I feel I took a mistake in loop statement. Would you mind helping me out? Thanks in advance.

DataParadigms DataParadigms · Accepted Answer · 2012-05-30T12:21:02

Right now you're always using the same data set as the input to aaaa and you're not changing this dataset with each loop. Thus, you'll always get Add20 only as this is what the last iteration of the loop will do.

A simple fix to this would be:

data append;
 set aa33;
run;

%MACRO DO_LIST;
%DO I=1 %TO 20;
data append; 
 set append;
 if A1 =i or
 A2 =i or
 A3 =i or
 .....
 A10 =i then Add&I=I ; 
RUN;
%END;
%MEND DO_LIST;
%DO_LIST;

You want pretty much add a column to your dataset each time the loop runs as opposed to entirely replacing it with the original dataset (aa33) and the results of only the current iteration.

If you know the max # is 20, the following should work without a macro

data test;
 set aa33;
 array add[20] 1. add1 - add20;
 array a[*] a:;

do i = 1 to dim(a);
  value = a[i];
  add[value] = 1;
end;
run;

I think that's what you're looking for, it'd help if you'd fill in at least the first two full rows of your example.

SAS macro loop and dummy variable

1 Answers