*** This file is copied from Brendan Halpin's website, 
**      http://www.ul.ie/sociology/brendan.halpin.html .


** It can be run as an include file to define the macro ffactor. 

* Jul 27 1998 16:00:26
* Macros for Loglinear Analysis course, August 1998.

* 1: zFACTOR: creates a vector of dummy (indicator) variables from 
*    a single categorical variable.
*    Example: "factor job jb 4" creates jb1 jb2 jb3 and jb 4, with 
*    values of zero and one depending on the value of job, a 4-value 
*    categorical variable.



*-----------------------------------------------------------------.
define factor (!pos !tok(1)
              /!pos !tok(1)
              /!pos !tok(1)).

* fac-var, new vector, number of values.

* Jul 15 1998 14:15:13
  Creates a vector-suitable set of dummy variables from
  a categorical variable. Errors will be generated if the 
  categorical value has non-missing values outside the range 
  1 -- arg-3. Existing variables with the same names will
  be overwritten.

* Create/initialise-to-zero the dummy vector.
!DO !i = 1 !TO !3
compute !concat(!2,!i)=0.
!DOEND

vector dumm = !concat(!2,1) to !concat(!2,!3) .
if not missing(!1) dumm(!1)=1.

!enddefine.




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