Cycling through all variables

1
votes

I started to learn SAS here fairly recently and am getting the basics down pretty well, but have a question regarding something that is a little outside of my current realm of knowledge. Does anyone happen to know of a way to cycle through all variables in a SAS dataset? I know how to run a do loop/array on variables in a range (x1-x99), but ideally would like to look at every variable without having to rename any variables. Basically, I'm looking to run through a dataset and change variable values when the current value = 'True'/'False'. My guess is that I'll need to use proc contents in someway here, but not really sure how to go about using it correctly. Any tips/insight would be greatly appreciated. Thanks!

2
sas

2 Answers

4
votes

You can create an array of non-similarly-named variables. You're on the right track with PROC CONTENTS, although you also can use dictionary.columns or sashelp.vcolumn, which contain basically the same information.

proc sql;
select name into :collist separated by ' ' 
from dictionary.columns
where memname='DATASETNAME' and libname='LIBNAME' and <other criteria>;
quit;

The variables have to be all of the same type (char/numeric) so you may want to include a criterion of variable type in your query, plus any other limiting factor you may need.

That will create a list, &collist., in a macro variable you can use in your array

array vars &collist.;

and now you can loop over the array.

You may also be able to cheat things, if all of your variables are the same type, and you know the order is fixed . The double dash list (x1--x99) is 'in variable order, all variables from x1 to x99' and doesn't require numeric suffixes or anything like that.

Finally, you also might be able to write a format in PROC FORMAT to accomplish what you need, depending on what you are intending to do (mapping TRUE to 1 and FALSE to 0 or something like that).

1
votes

Adding to Joe's answer: you can overcome the requirement that all variables should be of the same type. For that you can use macro loop instead of array. Firstly you need to define the macro:

%macro loop;
    %do i=1 %to %sysfunc(countw(&collist));
      ....
      <here goes your code for changing values, where instead of a variable name 
       you use macro function %scan(&collist,&i)>
      ....
    %end;
%mend loop;

and now you can paste %loop into the DATA step where you're going to process all variables.