topic Re: Updating global macro variable based on a condition in SAS Programming

Updating global macro variable based on a condition

DocMartin — Thu, 29 Jun 2017 18:54:06 GMT

I have a global variable called "switch", which by default is set to 'N'; If a certain condition occurs then I'd like switch be = 'Y'. The code I'm using always changes switch to 'Y', regardless of the condition. That's not right. Here's my code: data _NULL_; %let switch = N; if rand('UNIFORM') > 0.3 then do; %let switch = 'Y'; end; %put &switch; run; Any ideas? Thanks!

Re: Updating global macro variable based on a condition

art297 — Thu, 29 Jun 2017 19:11:57 GMT

Two problems: 1 you change it from N to 'Y' (why do you add quotes for Y?)

2 You use %let let in a datastep, when you should use call symput

What condition do you really want to use? Surely, not just randomly like shown in your code.

Art, CEO, AnalystFinder.com

Re: Updating global macro variable based on a condition

Astounding — Thu, 29 Jun 2017 19:47:44 GMT

%LET statements are never part of a DATA step. You might as well have coded:

%let switch = N;

%let switch = 'Y';

%put &switch;

data _NULL_;

if rand('UNIFORM') > 0.3 then do;

end;

run;

That reflects what your program is actually doing. However, the good news is that there are interfaces between a DATA step and macro language. You could instead code:

%let switch = N;

data _null_;

if rand('UNIFORM') > 0.3 then call symput('switch', 'Y');

run;

%put &switch;

Re: Updating global macro variable based on a condition

DocMartin — Thu, 29 Jun 2017 19:47:46 GMT

The quotes around Y are a mistake. I wasn't aware (but now am!) that I can't use %let in the data step. So how would I use call symput to do what I intended? Thanks!

Re: Updating global macro variable based on a condition

DocMartin — Thu, 29 Jun 2017 19:52:44 GMT

That works! Thanks.