Using Loop Index in Name

jl1005 — Tue, 06 Mar 2018 21:05:12 GMT

Hi,

Suppose I have the following code:

proc iml;
	class_1 ={1 0 2,
		  2 3 2};
	class_2 ={4 2 3,
		  2 6 2};
	div ={1	2 4,
 	      6	8 10};
	new_1 = class_1 / div;
	new_2 = class_2 / div;
	print new_1;
	print new_2;

I want to set up a loop to reduce the code. So something like

	do i = 1 to 2;
		new_i = class_i / div;
		print new_i;
		end;

What's the proper way to extract the value of i and use it as an actual value?

Thank you.

Re: Using Loop Index in Name

Rick_SAS — Tue, 06 Mar 2018 21:24:02 GMT

For your example in which all variables are the same size, I recommend "flattening" the data into row vectors and storing the matrices as rows in a matrix. For your example, it would look like this:

nr = 2;  /* number of rows */
nc = 3;  /* number of cols */
nMatrices = 2;  /* total number of matrices being stored */

class = {
1 0 2  2 3 2,  /* first 2x3 matrix */
4 2 3  2 6 2}; /* second 2x3 matrix */

div ={1 2 4  6	8 10};  
new = class / div;

/* if you need to print or use as matrices, use SHAPE: */
do i = 1 to nMatrices;
   newM = shape(new, nr, nc);
   print newM;
end;

Although I don't recommend it, if you insist on using symbols that have numerical suffixes, you can use the VALUE and VALSET functions.

do i = 1 to 2;
   cName = "class_" + strip(char(i));
   c = value(cName);    /* get value of class_i */
   new = c / div;
   print new;
   /* if necessary, use VALSET to create new_i */
end;

topic Using Loop Index in Name in SAS/IML Software and Matrix Computations

Using Loop Index in Name

Re: Using Loop Index in Name