The TREE Procedure

Fisher (1936)’s iris data give sepal and petal dimensions for three different species of iris. The data, which are available in the Sashelp library, are clustered by kth-nearest-neighbor density linkage by using the CLUSTER procedure with K=8. Observations are identified by species ('Setosa', 'Versicolor', or 'Virginica') in the tree diagram, which is oriented with the height axis horizontal.

The following statements produce the results shown in Output 105.2.1:

title 'Fisher (1936) Iris Data';
ods graphics on;

proc cluster data=sashelp.iris method=twostage print=10
             outtree=tree k=8 noeigen;
   var SepalLength SepalWidth PetalLength PetalWidth;
   copy Species;
run;

proc tree data=tree horizontal lineprinter pages=1 maxh=10;
   id species;
run;

The PAGES=1 option specifies that the tree diagram extend over one page from tree to root. Since the HORIZONTAL option is also specified, the horizontal extent of the diagram is one page. The number of vertical pages required for the diagram is dictated by the number of leaves in the tree.

The MAXH=10 limits the values displayed on the height axis to a maximum of 10. This prunes the tree diagram so that only the portion from the leaves to level 10 is produced. The line printer plot is not displayed.