topic Re: How to put the dot product of two vector macro variables into data step equations? in SAS Programming

How to put the dot product of two vector macro variables into data step equations?

YutongHu — Thu, 07 Dec 2017 03:11:58 GMT

&effects and &estimate are regression results stored in vector macro variables.

As shown in the pictures above, &effects is the vector variable with the names of effects.

&estimate are the vector of coefficients.

say &effects is "a b c d e f g".

&estimate is "1 2 3 4 5 6 7"

How can I use these two macro variables to create a data step equation that equals to the dot product of the two vectors?

Here's the code that I tried, but it did not produce the correct result.

%do i=1 %to %sysfunc(countw(&effects));
%let effects&i = %scan(&effects, &i, %str( ));
%end;

%do i=1 %to %sysfunc(countw(&estimate));
%let estimate&i = %scan(&estimate, &i, %str( ));
%end;

%let total1=&effects1*estimate1;
%let largeN=%sysfunc(countw(&effects));

%do i=2 %to %sysfunc(countw(&effects));
%let total&i = total%eval(&i-1).+&effects&i*&estimate&i;
%end;

%put &total&largeN; [<-this should be the yhat definition, it is an expression like a*1 + b*2 + c*3 + d*4 + e*5 + f*6 + g*7]

data option2;
set opion1;
yhat=&total&largeN; [<-this equation should be the same as "yhat=a*1 + b*2 + c*3 + d*4 + e*5 + f*6 + g*7"]
run;

Can anyone help me to solve this problem? Thank you so much!

Re: How to put the dot product of two vector macro variables into data step equations?

Astounding — Thu, 07 Dec 2017 03:45:11 GMT

Well, you could cut out a few pieces in this way:

data option2;

set option1;

yhat =

%do i=1 %to %sysfunc(countw(&effects));

%scan(&effects, &i) * %scan(&estimate, &i)

%if &i < %sysfunc(countw(&effects)) %then + ;

%end;

;

run;

This does have to be inside a macro definition, to permit %if and %do.

Re: How to put the dot product of two vector macro variables into data step equations?

Reeza — Thu, 07 Dec 2017 04:28:20 GMT

I would say, don’t create this problem in the first place.

There are multiple ways to score new data, this doesn’t seem like a good approach.

Assuming that’s what you’re doing of course.

Re: How to put the dot product of two vector macro variables into data step equations?

ballardw — Thu, 07 Dec 2017 16:09:32 GMT

Please explain what the overall purpose of the generated data step code.

If your macro variable lists came from a data set it may be that using that data set and some data transformation in a data step will work in a much cleaner manner.

If you are going to use multiple identical calls such as

%sysfunc(countw(&effects))

perhaps you would be better off calling that once and assigning the value to another macro variable. Then you could make the code a little cleaner:

%do I = 1 to &EffectCount;

Re: How to put the dot product of two vector macro variables into data step equations?

jint83 — Thu, 07 Dec 2017 18:39:00 GMT

Speaking on behalf of the poster. These macros, did not come from a dataset, so the question cannot be avoided, as the macros definitions come from SAS GLM select outputs:

https://support.sas.com/documentation/cdl/en/statug/63347/HTML/default/viewer.htm#statug_glmselect_sect022.htm

I don't know the answer to poster's question, but I do think the question is an important one that begs to be addressed within the framework of the poster's question.

Re: How to put the dot product of two vector macro variables into data step equations?

ballardw — Fri, 08 Dec 2017 00:18:30 GMT

If @jint83 is correct and this is coming from proc glmselect then help us out by running the model and then posting the result of

%put _user_;

This will give us the actual names and contents of the macro variables.

Or try adding a line something like this to your code (before the run statement)

   ods output parameterestimates= work.parms;

Which will create a data set with the effect and the parameters.

You don't mention if by groups are involved but for a single model

data _null_;
   set work.parms end=eof;
   length longstr $ 500;
   retain longstr;
   longstr = catx(' + ',longstr, catx('*',effect,estimate));
   call symputx('Formula',longstr);
run;

%put &formula;

appears to do what you want.

Re: How to put the dot product of two vector macro variables into data step equations?

YutongHu — Fri, 08 Dec 2017 03:23:17 GMT

I tried the code, but it still did not work. Thank you anyway.

Re: How to put the dot product of two vector macro variables into data step equations?

YutongHu — Fri, 08 Dec 2017 03:28:42 GMT

The problem was that I predicted the model using sample A, but I also want to use the model to test the accuracy of the model on sample B. However, I only know the step that directly produces predicted yhat for sample A. That is why I need to create a formula by macro variables.

Re: How to put the dot product of two vector macro variables into data step equations?

YutongHu — Fri, 08 Dec 2017 03:32:48 GMT

Hi, the problem was that I predicted the model from sample A.

Let's say the model is yhat=a + b*1 + c*2

I want to calculate yhat not only for the observations in sample A, but also for the observations in sample B.

Is there a simpler way that I can use to avoid using macro variables?

Thank you!

Re: How to put the dot product of two vector macro variables into data step equations?

Reeza — Fri, 08 Dec 2017 03:39:18 GMT

See the various methods here.

https://blogs.sas.com/content/iml/2014/02/19/scoring-a-regression-model-in-sas.html