How to make a SAS macro run through variables/columns?

Question

I am trying my hand at SAS macros for the first time. My basic question is: I have a dataset with some 10000 variables. I need to take each column individually, create a new conditional variable, store the results, then move to the next column. These columns are not sequentially ordered. What is the syntax SAS uses to identify a column (similar to how "_N_" would identify a row)?

Here is more information. The data looks something like this:

ID  v1   v2   v3  ... v10000
01  3.2  1.5  7.8 ...   4.2
02  1.1  4.5  1.9 ...  10.7
..
 N  2.5  1.5  4.9 ...   7.3

I need to look at the values of v1, count how many obs are above a value x and how many are below a value x, record those numbers in a dataset, then move onto v2, v3, ... v10000. In the end, I'd have a dataset that would show the number of obs above value x and number of obs below value x for each of my 10000 variables.

I have written the code as I would have written it for one variable in standard SAS code and it works, and now my intention is to convert that code into macro code, but I do not know how to construct a loop that would move from one column to the next.

Any help or references you could give would be greatly appreciated.

Thanks.

Answer 1

%LET CUTOFF = 3.1415926 ; /* set this as your 'cutoff' value */

data counters ;
  set mydata end=eof ;

  array vi{*} v1-v10000 ; /* incoming values */
  array vc{*} c1-c10000 ; /* counters */

  retain vc . ;

  do i = 1 to dim(vi) ;
    if vi{i} >= &CUTOFF then vc{i} + 1 ;
  end ;

  if eof then output ;

  keep c1-c10000 ;
run ;