Using the Annotate Facility
The Annotate facility enables you to enhance graphics output
produced by PROC NETDRAW. To use this facility you must create
an Annotate data set, which contains a set of graphics
commands that can be superimposed on the network diagram. This
data set has a specific format and must contain key variables
as described in
SAS/GRAPH Software: Reference, First Edition.
That chapter lists the variables that are required
in this data set and explains the coordinate systems used
by the Annotate facility. The present section explains the
use of data coordinates specifically
with reference to the NETDRAW procedure.
When annotating a graph produced by any of the graphics procedures,
it is helpful to use data coordinates that refer to the
data values corresponding to the graph that is being annotated. For
example, if you want to label a particular node of a network diagram
with additional text, you can position the text accurately if
you use data coordinates instead of screen coordinates.
With respect to PROC NETDRAW, the Annotate facility uses the
_X_ and _Y_ values in the Layout data set as the
basis for the data coordinate system. To use this feature, you can
invoke PROC NETDRAW (with the NODISPLAY option, if necessary) for
the given network to produce the Layout data set that contains
the _X_ and _Y_ coordinates for each node of the network.
This data set can then be used to create the required Annotate
data set containing the graphics commands positioning the
primitives appropriately on the diagram using the data coordinates.
See Example 5.16 and Example 5.17 for
illustrations of this feature.
Note: The data coordinate system enables you to annotate the graph
even if it spans multiple pages. However, each annotation must be
entirely contained within a given page. For example, you cannot
annotate a line on the network diagram that runs from one page of
the diagram to another.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.