Use formula for values of matrix elements

[MDaniel]

Is there a way to write the 5th line below so that it works (while keeping it within a single expression / single line) ?

More generally, how can a vector be initiated by specifying formulas instead of values for each element?

proc iml;
	x = j(3,2,.);
	do i = 1 to nrow(x);
		/*this doesn't work*/
		x[i,] = { i 0 };

		/*this does work, but it's an extra line */
		x[i,1] = i;
		x[i,2] = 0;
	end;
quit

[Rick_SAS · Accepted solution]

The direct answer to your question is to use the horizontal concatenation operator (||)

x[i,] = i || 0;

as described in the article "How to build a vector from expressions."

Of course, for this example, you don't need a loop at all:

proc iml;
x1 = T( 1:3 );
x2 = j(nrow(x1), 1, 0);
x = x1 || x2;