topic Re: IF clause in SAS Programming

IF clause

Babloo — Mon, 25 May 2015 11:12:04 GMT

I need to extract the data which does not have the products 'auto' and 'cd'. I tried the code below,

data have;

input product $;

datalines;

auto

WIS

;

run;

data want;

set have;

if product ne 'auto' or product ne 'Cd' then output ;

run;

It is not working. Any possibilities to achive this one If (or where) clause? I know we can achive with two if clauses like below.

if product ne 'auto';

if product ne 'Cd';

Thanks for the suggestions.

Re: IF clause

Ksharp — Mon, 25 May 2015 11:55:18 GMT

if product not in ('auto' 'Cd') then output ;

Re: IF clause

sbb — Mon, 25 May 2015 15:18:12 GMT

For the "help me understand why my code doesn't work?" perspective.....

Review your use of OR versus AND in your IF <expression> THEN OUTPUT; statement.

However, also consider that the two IF statements, as you have them coded, will work correctly, given your desired result.

Re: IF clause

Tom — Mon, 25 May 2015 16:18:08 GMT

You are just having a logic problem.

Your first conditional is of the form (NOT A or NOT B) Since it is never possible for A and B to be true at the same time (this would mean that product is both 'auto' and 'Cd' at the same time) your condition is always true.

Your second is of the form (NOT A AND NOT B) and so actually succeeds in sub-setting the data.

So instead of

if product ne 'auto' or product ne 'Cd' then output ;

you want

if product ne 'auto' AND product ne 'Cd' then output ;

You can reformulate (NOT A AND NOT B) to NOT (A OR B) using basic logic and get

if not (product = 'auto' OR product = 'Cd') then output ;

This can also be written as

if product not in ('auto','Cd') then output ;

Re: IF clause

yukclam9 — Mon, 25 May 2015 19:06:25 GMT

i think the statement could be simplified by eliminating the output statement.

that is,

if product not in ('auto' 'Cd') ;

Re: IF clause

Ron_MacroMaven — Tue, 26 May 2015 19:15:36 GMT

Hi Tom

Yes, I agree this a logic problem.

and De Morgan's Rules of conversion of negations are non-trivial.

Here is a program to help others understand nand and nor.

Truth Table - sasCommunity

Ron Fehd logical maven