topic Re: Dynamically change the variable attributes in SAS Programming

Dynamically change the variable attributes

SAS_inquisitive — Wed, 09 Mar 2016 18:00:36 GMT

This macro code creates the code below. I want to create only one length statement and only variable names changing dynamically.

data test;
input var1 $ var2 $;
cards;
 1 4
 2 5
 3 6
 ;

%macro m;

	data test;
		%do i= 1 %to 2;
			length var&i $ 10.;
		%end;

		set test;
	run;

%mend m;

%m

/* cod generated */

data test;
	length var1 $ 10.;
	length var2 $ 10.;
	set test;
run;

/* desired code */

data test;
	length var1 $ 10.
           var2 $ 10.;
	set test;
run;

Re: Dynamically change the variable attributes

data_null__ — Wed, 09 Mar 2016 18:12:04 GMT

Just move the word LENGTH before %DO and semi-colon after %end;

Re: Dynamically change the variable attributes

data_null__ — Wed, 09 Mar 2016 18:13:15 GMT

Or how about just do
length var1-var2 $10;

Re: Dynamically change the variable attributes

Astounding — Wed, 09 Mar 2016 18:13:41 GMT

Definitely a worthwhile technique to learn!

Here's what you have now:

%do i=1 %to 2;

length var&i $ 10.;

%end;

Here's what the replacement would look like (notice the dot is not required when defining length, only for formats):

length

%do i=1 %to 2;

var&i

%end;

$ 10;

Good luck.

Re: Dynamically change the variable attributes

SAS_inquisitive — Wed, 09 Mar 2016 18:29:29 GMT

@data_null__ @Astounding. Thank you. May be I could start another thread. What if variables are not var1 and var2 (ie. can not referenced by macro variable &i) such as x and y and I need to change their attributes inside macro definition.

data test;
input x $ y $;
cards;
 1 4
 2 5
 3 6
 ;

Re: Dynamically change the variable attributes

Astounding — Wed, 09 Mar 2016 18:35:04 GMT

The answer depends on how the variable names are stored. For example, do you have a macro variable holding a list of variable names:

%let var_list = x var1 y;

Do you have a data set where a DATA step variable takes on values of "x" "var1" and "y"?

How do you expect to provide the list of variable names?

Re: Dynamically change the variable attributes

SAS_inquisitive — Wed, 09 Mar 2016 19:37:02 GMT

@ Astounding. Yes, the horizontal list as you mentioned.
%let var_list=x y;

Re: Dynamically change the variable attributes

Astounding — Wed, 09 Mar 2016 19:52:04 GMT

When you already have all the variable names assembled in a single macro variable, I would skip the looping:

length &var_list $ 10;