%include data(iris);
title 'Iris data: Stepwise discriminant analysis';
 
proc stepdisc data=iris;
     classes species;
     var sepallen sepalwid petallen petalwid;

proc plot;
   plot petallen * petalwid = spec_no;	*-- species number as symbol;
 
* Now, try two derived measures: petal size and elongation;
title2 'Size and elongation';
data iris;
   set iris;
   size = log (petallen*petalwid);
   elong= log (petallen/petalwid);
proc plot;
   plot size * elong = spec_no;
 
proc stepdisc data=iris include=2;
     classes species;
     var size elong petallen petalwid sepallen sepalwid;

*-- Compare error rates of classification;
proc discrim data=iris method=normal short;
     classes species;
     var sepallen sepalwid petallen petalwid;

proc discrim data=iris method=normal short;
     classes species;
     var size elong;