06-09-2016 03:20 PM
I have two variables, X and Y, plus another variable S. X and Y are integers in the range 1-7. S is a character variable that takes the value '1' and some others. I want to create a series of flags, A1-A4, according to these rules.
I first wrote this:
DATA Test; SET Source; ARRAY A A1-A4 (0 0 0 0); IF S = '1' THEN A[MIN(4,MAX(X,Y))] = 1; ELSE A[MIN(4,Y)] = 1; RUN;
As I read that, it should change only one of the A1-A4 flags for each record. But what I find is that ALL of the values of A1-A4 get set to 1.
If I do this,
DATA Test; SET Source; A1 = 0; A2 = 0; A3 = 0; A4 = 0; ARRAY A A1-A4; IF S = '1' THEN A[MIN(4,MAX(X,Y))] = 1; ELSE A[MIN(4,Y)] = 1; RUN;
I get what I want. What is the difference?
06-10-2016 08:03 AM
Thanks to all who replied. I seldom use the ability to intialize arrays, and I see that there were implications of doing that which I didn't realize.
Thanks also to those who showed me how to make the code more compact. Those are clever uses of SAS functions. I'm not sure if I will use them. I fear that a few years from now, someone (possibly me) will look at the code and say, "What the heck does that do?" I don't want my code to be more clever than my ability to understand it!
06-09-2016 07:32 PM
ARRAY A A1-A4 (0 0 0 0);
initialises the values only once: when the array is created.
There are 2 cases when array values are not reset in the data step loop: when they are temporary, and when their values are initialised.
06-10-2016 05:14 AM
If it helps, you can shrink your if clauses:
data source; s="1"; x=3; y=3; output; s="2"; x=1; y=6; output; run; data test; set source; array a (0 0 0 0); a[min(4,max(x,y))]=ifn(s='1',1,0); run;
06-10-2016 06:06 AM
Side note: The specifiction of an initial value for one array variable implies RETAIN for all variables of the array, including those which are not initialized.
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