How to create a loop-within-loop macro

Hugo_1_ — Wed, 24 Oct 2018 16:05:16 GMT

Hello,

I am having a lot of trouble creating several dummy-variables with two loops, and I have no idea how to do it.

The goal is to make dummy-variables from categorical variables recorded at specific times.

As of now (for 5 years with 5 categories), to do it manually it would be like:

data tmp;

set data1;

if y_1=0 then cat0_time_0=1; else cat0_time_0=0;

if y_2=0 then cat0_time_1=1; else cat0_time_1=0;

if y_3=0 then cat0_time_2=1; else cat0_time_2=0;

if y_4=0 then cat0_time_3=1; else cat0_time_3=0;

if y_5=0 then cat0_time_4=1; else cat0_time_4=0;

if y_1=1 then cat1_time_0=1; else cat1_time_0=0;

if y_2=1 then cat1_time_1=1; else cat1_time_1=0;

if y_3=1 then cat1_time_2=1; else cat1_time_2=0;

if y_4=1 then cat1_time_3=1; else cat1_time_3=0;

if y_5=1 then cat1_time_4=1; else cat1_time_4=0;

if y_1=2 then cat2_time_0=1; else cat2_time_0=0;

if y_2=2 then cat2_time_1=1; else cat2_time_1=0;

if y_3=2 then cat2_time_2=1; else cat2_time_2=0;

if y_4=2 then cat2_time_3=1; else cat2_time_3=0;

if y_5=2 then cat2_time_4=1; else cat2_time_4=0;

if y_1=3 then cat3_time_0=1; else cat3_time_0=0;

if y_2=3 then cat3_time_1=1; else cat3_time_1=0;

if y_3=3 then cat3_time_2=1; else cat3_time_2=0;

if y_4=3 then cat3_time_3=1; else cat3_time_3=0;

if y_5=3 then cat3_time_4=1; else cat3_time_4=0;

if y_1=4 then cat4_time_0=1; else cat4_time_0=0;

if y_2=4 then cat4_time_1=1; else cat4_time_1=0;

if y_3=4 then cat4_time_2=1; else cat4_time_2=0;

if y_4=4 then cat4_time_3=1; else cat4_time_3=0;

if y_5=4 then cat4_time_4=1; else cat4_time_4=0;

run;

y_3=4 means "Year 3 for category 4" and so on.

But I need to have it more macro-based, so that one only need to specify the maximum amount of categories and years. However, I just can't get it to work.

The "closest" I have gotten is through this attempt:

%MACRO time_categorical_to_binary(time_max=, number_cat=);

data tmp;

set data1;

%DO i = 0 %to &time_max;

%DO j = 0 %to &number_cat;

if y_&i.=1 then cat_&j._time_&i.=1; else cat_&j._time_&i.=0;

run;

%END;

%MEND time_categorical_to_binary;

%time_categorical_to_binary(time_max=4, number_cat=5);

But it seems like SAS doesn't like it when trying to create two indicators to the same variable.

Does anyone have any ideas how to make this doable?

I use SAS 9.4

Re: How to create a loop-within-loop macro

DBailey — Wed, 24 Oct 2018 16:26:33 GMT

I removed what may be an extra underscore in cat&i....but have you tried this:

%MACRO time_categorical_to_binary(time_max=, number_cat=);
%DO i = 0 %to &time_max;
%DO j = 0 %to &number_cat;
if y_&i.=1 then cat&j._time_&i.=1; else cat&j._time_&i.=0; 
%END;
%END;
%MEND time_categorical_to_binary;


data tmp;
set data1;
%time_categorical_to_binary(time_max=4, number_cat=5);
run;

Re: How to create a loop-within-loop macro

Kurt_Bremser — Wed, 24 Oct 2018 16:34:03 GMT

The run; must not be in the %do loop.

Re: How to create a loop-within-loop macro

Hugo_1_ — Thu, 25 Oct 2018 07:35:03 GMT

It worked! Thank you!

I also noticed that I had missed to have

if y_&i.=&j. then cat&j._time_&i.=1; else cat&j._time_&i.=0;

instead of

if y_&I.=1 then cat&j._time_&i.=1; else cat&j._time_&i.=0;

But that was easily adjusted. Now everything works perfectly!

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