topic Re: AND/ OR conditions in SAS Programming

AND/ OR conditions

Ronein — Wed, 20 Oct 2021 06:59:40 GMT

Hello

I want to ask if option1 and option2 are doing same or there is a difference?

Thanks

/***option1***/
IF x=5 OR (X=2 AND W=3) OR (X=2 AND W=8) AND Z=9 then Ind=1;
/***option2***/
IF (x=5 OR (X=2 AND W=3) OR (X=2 AND W=8)) AND Z=9 then Ind=1;

Re: AND/ OR conditions

Astounding — Wed, 20 Oct 2021 07:11:17 GMT

Different...
Option 1 sets IND to 1 whenever X is 5. AND gets evaluated before OR without parentheses.

Option 2 requires Z to be 9 to set IND to 1.

Re: AND/ OR conditions

Ronein — Wed, 20 Oct 2021 07:33:49 GMT

May anyone explain the calculation of Ind_a

I don't understand how it works,

why X=5 W=100 Z=90 get ind_a=1??

Data ttt;
input x w z;
cards;
5 100 9
5 100 90
8 90 9
;
Run;

Data wanted;
set ttt;
IF x=5 OR (X=2 AND W=3) OR (X=2 AND W=8) AND Z=9 then Ind_a=1;
IF (x=5 OR (X=2 AND W=3) OR (X=2 AND W=8)) AND Z=9 then Ind_b=1;
Run;

Re: AND/ OR conditions

Kurt_Bremser — Wed, 20 Oct 2021 08:34:05 GMT

As already mentioned, AND is evaluated first, so this:

(X=2 AND W=8) AND Z=9

is calculated first; it is equivalent to

X=2 AND W=8 AND Z=9

all three conditions need to be satisfied for this part to become true. In your data, this is never the case.

Similarly, the other AND is evaluated (the brackets are not necessary, but they help in keeping the code clear).

Then come the ORs, and since X=5 is satisfied in the first two observations, the whole condition will become true.

In more readable form, your condition is this:

if
  x=5
  or (
    X=2 and W=3
  ) 
  or (
    X=2 and W=8 and Z=9
  )
then Ind_a=1;