topic Re: Creating Variable Names dynamically in SAS Programming

Creating Variable Names dynamically

warnost — Wed, 09 Jan 2013 16:46:02 GMT

Hi,

I often have to transform large sets of variables for use in regression, and how I normally hand the task is to manually code arrays for each of the new transformed variables, similar to the this example:

data example;

input A B C;

array var

A B C;

array change

r_A r_B r_C;

do i = 1 to dim(change);

change = var/lag(var) - 1;

end;

datalines;

10 20 30

15 5 60

25 30 10

run;

This becomes very tedious when you have large numbers of variables. I was hoping to get to something like the following, but I have not been able to create functioning code. Not sure if a macro loop is the right way to go, been trying to use a combination of vname and cat functions but no luck so far.

data example;

input A B C;

array var

_NUMERIC_;

array change

/*code that adds the prefix "r_" to all variables in var[]*/;

do i = 1 to dim(change);

change = var/lag(var) - 1;

end;

datalines;

10 20 30

15 5 60

25 30 10

run;

Any ideas?

Re: Creating Variable Names dynamically

Linlin — Wed, 09 Jan 2013 17:07:47 GMT

is the example helpful?

proc sql noprint;
select name into : names separated by ' '
   from dictionary.columns
    where libname="SASHELP" and memname="CLASS" and type="num";
select cats('r_',name) into : r_names separated by ' '
   from dictionary.columns
    where libname="SASHELP" and memname="CLASS" and type="num";

quit;
data want;
set sashelp.class;
array var

&names;
array change

&r_names;
do i = 1 to dim(change);
change = var/lag(var) - 1;
end;
drop i;
proc print;run;

Re: Creating Variable Names dynamically

data_null__ — Wed, 09 Jan 2013 17:38:54 GMT

Consider using new observations for the transformation. With an ID to sort them.

TRANSFORM

NONE

LOG

SQRT

Re: Creating Variable Names dynamically

warnost — Wed, 09 Jan 2013 18:16:39 GMT

I tried this code but I get the following error in my log:

2335 array var

&names;

200

WARNING: Apparent symbolic reference NAMES not resolved.

2336 array change

&r_names;

200

WARNING: Apparent symbolic reference R_NAMES not resolved.

ERROR 22-322: Syntax error, expecting one of the following: a name, a numeric constant, $, (, ;,

_ALL_, _CHARACTER_, _CHAR_, _NUMERIC_, _TEMPORARY_.

ERROR 200-322: The symbol is not recognized and will be ignored.

I am using the code exactly, just with sashelp and class replaced with the library and data set that I am using. I am not familiar with proc sql, is this the correct implementation?

Thanks!

Re: Creating Variable Names dynamically

warnost — Wed, 09 Jan 2013 18:17:58 GMT

I will consider using new observations but it will require me to rethink the way I do the regression and other procedures. Thank you!

Re: Creating Variable Names dynamically

Linlin — Wed, 09 Jan 2013 18:25:48 GMT

where libname="SASHELP" and memname="CLASS" and type="num";

The red parts have to be upcase.

Re: Creating Variable Names dynamically

warnost — Wed, 09 Jan 2013 18:47:36 GMT

That worked! Thank you!