PROC TREE: PROC TREE Statement :: SAS/STAT(R) 9.2 User's Guide, Second Edition

The TREE Procedure

PROC TREE Statement

PROC TREE <options> ;

The PROC TREE statement starts the TREE procedure.

The options that can appear in the PROC TREE statement are summarized in Table 91.1.

Table 91.1 PROC TREE Statement Options
Option	Description
Data Sets
DATA=	specifies input data set
DOCK=	specifies that small clusters not be counted in OUT= data set
LEVEL=	defines disjoint cluster in OUT= data set
NCLUSTERS=	specifies number of clusters in OUT= data set
OUT=	specifies output data set
ROOT=	displays root of a subtree
Cluster Heights
HEIGHT=	specifies variable for the height axis
DISSIMILAR	specifies that height values indicate dissimilarity
SIMILAR	specifies that height values indicate similarity
Horizontal Trees
HORIZONTAL	specifies that height axis be horizontal
Sort Order
DESCENDING	reverses sort order
SORT	sorts children by HEIGHT variable
Displayed Output
INC=	specifies increment between tick values
LINEPRINTER	displays tree by using line printer graphics
LIST	displays all nodes in tree
MAXHEIGHT=	specifies maximum value on axis
MINHEIGHT=	specifies minimum value on axis
NOPRINT	suppresses display of tree
NTICK=	specifies number of tick intervals
Graphics
CFRAME=	specifies color of the frame
DESCRIPTION=	specifies catalog description
GOUT=	specifies catalog name
HAXIS=	customizes horizontal axis
HORDISPLAY=	displays horizontal tree with leaves on right
HPAGES=	specifies number of pages to expand tree horizontally
LINES=	specifies line color and thickness, dots at nodes
NAME=	specifies name of graph in catalog
VAXIS=	customizes vertical axis
VPAGES=	specifies number of pages to expand tree vertically
Line Printer Graphics
PAGES=	specifies number of pages
POS=	specifies number of column positions
SPACES=	specifies number of spaces between objects
TICKPOS=	specifies number of column positions between ticks
FILLCHAR=	specifies fill character between unjoined leaves
JOINCHAR=	specifies character displayed between joined leaves
LEAFCHAR=	specifies character representing clusters with no children
TREECHAR=	specifies character representing clusters with children

CFRAME=color

specifies a color for the frame, which is the rectangle bounded by the axes.

DATA=SAS-data-set

specifies the input data set defining the tree. If you omit the DATA= option, the most recently created SAS data set is used.

DESCENDING

DES

reverses the sorting order for the SORT option.

DESCRIPTION=entry-description

specifies a description for the graph in the GOUT= catalog. The default is "Proc Tree Graph Output."

DISSIMILAR

DIS

specifies that the values of the HEIGHT variable are dissimilarities; that is, a large height value means that the clusters are very dissimilar or far apart.

If neither the SIMILAR nor the DISSIMILAR option is specified, PROC TREE attempts to infer from the data whether the height values are similarities or dissimilarities. If PROC TREE cannot tell this from the data, it issues an error message and does not display a tree diagram.

DOCK=n

causes observations in the OUT= data set assigned to output clusters with a frequency of $\text{[math]}$ or less to be given missing values for the output variables CLUSTER and CLUSNAME. If the NCLUSTERS= option is also specified, DOCK= also prevents clusters with a frequency of $\text{[math]}$ or less from being counted toward the number of clusters requested by the NCLUSTERS= option. By default, DOCK=0.

FILLCHAR=’c’

FC=’c’

specifies the character to display between leaves that are not joined into a cluster. The character should be enclosed in single quotes. The default is a blank. The LINEPRINTER option must also be specified.

GOUT=<libref.>member-name

specifies the catalog in which the generated graph is stored. The default is WORK.GSEG.

HAXIS=AXISn

specifies that the AXIS $\text{[math]}$ statement used to customize the appearance of the horizontal axis.

HEIGHT=name

H=name

specifies certain conventional variables to be used for the height axis of the tree diagram. For many situations, the only option you need is the HEIGHT= option. Valid values for name and their meanings are as follows:

HEIGHT | H: specifies the _HEIGHT_ variable.
LENGTH | L: defines the height of each node as its path length from the root. This can also be interpreted as the number of ancestors of the node.
MODE | M: specifies the _MODE_ variable.
NCL | N: specifies the _NCL_ (number of clusters) variable.
RSQ | R: specifies the _RSQ_ variable.

See also the section HEIGHT Statement, which can specify any variable in the input data set to be used for the height axis. In rare cases, you might need to specify either the DISSIMILAR option or the SIMILAR option.

HORDISPLAY=RIGHT

specifies that the graph be oriented horizontally, with the leaf nodes on the right side, when the HORIZONTAL option is also specified. By default, the leaf nodes are on the left side.

HORIZONTAL

HOR

displays the tree diagram with the height axis oriented horizontally. The leaf nodes are on the side specified in the HORDISPLAY= option. If you do not specify the HORIZONTAL option, the height axis is vertical, with the root at the top. When the tree takes up more than one page, horizontal orientation can make the tree diagram considerably easier to read.

HPAGES=n1

specifies that the original graph be enlarged to cover $\text{[math]}$ pages. If you also specify the VPAGES= $\text{[math]}$ option, the original graph is enlarged to cover $\text{[math]}$ graphs. For example, if HPAGES=2 and VPAGES=3, then the original graph is generated, followed by $\text{[math]}$ more graphs. In these six graphs, the original is enlarged by a factor of 2 in the horizontal direction and by a factor of 3 in the vertical direction. The graphs are generated in left-to-right and top-to-bottom order.

INC=n

specifies the increment between tick values on the height axis. If the HEIGHT variable is _NCL_, the default is usually 1, although a different value can be specified for consistency with other options. For any other HEIGHT variable, the default is some power of 10 times 1, 2, 2.5, or 5.

JOINCHAR=’c’

JC=’c’

specifies the character displayed between leaves that are joined into a cluster. The character should be enclosed in single quotes. The default is 'X'. The LINEPRINTER option must also be specified.

LEAFCHAR=’c’

LC=’c’

specifies the character used to represent clusters having no children. The character should be enclosed in single quotes. The default is a period. The LINEPRINTER option must also be specified.

LEVEL=n

specifies the level of the tree defining disjoint clusters for the OUT= data set. The LEVEL= option also causes only clusters between the root and a height of $\text{[math]}$ to be displayed. The clusters in the output data set are those that exist at a height of $\text{[math]}$ on the tree diagram. For example, if the HEIGHT variable is _NCL_ (number of clusters) and LEVEL=5 is specified, then the OUT= data set contains five disjoint clusters. If the HEIGHT variable is _RSQ_ ( $\text{[math]}$ ) and LEVEL=0.9 is specified, then the OUT= data set contains the smallest number of clusters that yields an $\text{[math]}$ of at least 0.9.

LINEPRINTER

specifies that the tree diagram be displayed using line printer graphics.

LINES=( <COLOR=color> <WIDTH=n> <DOTS>)

specifies the color and the thickness of the lines of the tree, and whether a dot is drawn at each leaf node. Note that if the frame and the lines are specified to be the same color, PROC TREE selects a different color for the lines.

LIST

lists all the nodes in the tree, displaying the height, parent, and children of each node.

MAXHEIGHT=n

MAXH=n

specifies the maximum value displayed on the height axis.

MINHEIGHT=n

MINH=n

specifies the minimum value displayed on the height axis.

NAME=name

specifies the entry name for the generated graph in the GOUT= catalog. Note that each time another graph is generated with the same name, the name is modified by appending a number to make it unique.

NCLUSTERS=n

NCL=n

N=n

specifies the number of clusters desired in the OUT= data set. The number of clusters obtained might not equal the number specified if (1) there are fewer than $\text{[math]}$ leaves in the tree, (2) there are more than $\text{[math]}$ unconnected trees in the data set, (3) a multiway tree does not contain a level with the specified number of clusters, or (4) the DOCK= option eliminates too many clusters.

The NCLUSTERS= option uses the _NCL_ variable to determine the order in which the clusters are formed. If there is no _NCL_ variable, the height variable (as determined by the HEIGHT statement or HEIGHT= option) is used instead.

NTICK=n

specifies the number of tick intervals on the height axis. The default depends on the values of other options.

NOPRINT

suppresses the display of the tree. Specify the NOPRINT option if you want only to create an OUT= data set.

OUT=SAS-data-set

creates an output data set containing one observation for each object in the tree or subtree being processed and variables called CLUSTER and CLUSNAME showing cluster membership at any specified level in the tree. If you specify the OUT= option, you must also specify either the NCLUSTERS= or LEVEL= option in order to define the output partition level. If you want to create a permanent SAS data set, you must specify a two-level name (see "SAS Data Files" in SAS Language Reference: Concepts).

PAGES=n

specifies the number of pages over which the tree diagram (from root to leaves) is to extend. The default is 1. The LINEPRINTER option must also be specified.

POS=n

specifies the number of column positions on the height axis. The default depends on the value of the PAGES= option, the orientation of the tree diagram, and the values specified by the PAGESIZE= and LINESIZE= options. The LINEPRINTER option must also be specified.

ROOT=’name’

specifies the value of the NAME variable for the root of a subtree to be displayed if you do not want to display the entire tree. If you also specify the OUT= option, the output data set contains only objects belonging to the subtree specified by the ROOT= option.

SIMILAR

SIM

specifies that the values of the HEIGHT variable represent similarities; that is, a large height value means that the clusters are very similar or close together.

SORT

sorts the children of each node by the HEIGHT variable, in the order of cluster formation. See the DESCENDING option on for details.

SPACES=s

S=s

specifies the number of spaces between objects in the output. The default depends on the number of objects, the orientation of the tree diagram, and the values specified by the PAGESIZE= and LINESIZE= options. The LINEPRINTER option must also be specified.

TICKPOS=n

specifies the number of column positions per tick interval on the height axis. The default value is usually between 5 and 10, although a different value can be specified for consistency with other options.

TREECHAR=’c’

TC=’c’

specifies the character used to represent clusters with children. The character should be enclosed in single quotes. The default is 'X'. The LINEPRINTER option must also be specified.

VAXIS=AXISn

specifies that the AXIS $\text{[math]}$ statement be used to customize the appearance of the vertical axis.

VPAGES=n2

specifies that the original graph be enlarged to cover $\text{[math]}$ pages. If you also specify the HPAGES= $\text{[math]}$ option, the original graph is enlarged to cover $\text{[math]}$ pages. For example, if HPAGES=2 and VPAGES=3, then the original graph is generated, followed by $\text{[math]}$ more graphs. In these six graphs, the original is enlarged by a factor of 2 in the horizontal direction and by a factor of 3 in the vertical direction. The graphs are generated in left-to-right and top-to-bottom order.

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