stacking data in SAS - sas

Question

I am trying to rearrange my data but am having a difficult time. The data I have looks something like this:
date a b c
====================
1996 5 7 8
1997 4 2 3
1998 1 9 6
what I want is to rearrange the data (presumably using arrays) to get this:
date val var
=============
1996 5 a
1997 4 a
1998 1 a
1996 7 b
1997 2 b
1998 9 b
1996 8 c
1997 3 c
1997 6 c
So that I've essentially stacked the variables (a,b,c) along with the corresponding date and name of the variable.
Thanks in advance!

Answer 1

Use PROC TRANSPOSE to pivot the data.
First sort by DATE
proc sort data=have;
by date;
run;
Then use transpose
proc transpose data=have out=want(rename=(COL1=VAL _NAME_=VAR));
by date;
var a b c;
run;
Finally, it looks like you want this sorted by VAR, and then DATE
proc sort data=want;
by VAR date;
run;

Answer 2

Since you mention arrays, here's how you would achieve the result using them.
I would, however, use the proc transpose method in the answer from #DomPazz as procedures are generally easier to read and understand by others who may need to look at the code
/* create initial dataset */
data have;
input date a b c;
datalines;
1996 5 7 8
1997 4 2 3
1998 1 9 6
;
run;
/* transpose data */
data want;
set have;
array vars{*} a b c; /* create array of required values */
length val 8 var $8; /* set lengths of new variables */
do i = 1 to dim(vars); /* loop through each element of the array */
val = vars{i}; /* set val to be current array value */
var = vname(vars{i}); /* set var to be name of current array variable name */
drop a b c i; /* drop variables not required */
output; /* output each value to a new row */
end;
run;
/* sort data in required order */
proc sort data=want;
by var date;
run;