The Graph Template Language

Overview

At the heart of ODS Graphics lies the Graph Template Language. For example, all of the graphs that are created by the SAS analytical procedures and by the SAS/GRAPH Statistical Graphics Procedures are generated using GTL. Users who need to go beyond the graphs created by these SAS procedures can use GTL directly to design their graphs using the TEMPLATE and SGRENDER procedures. To successfully create or modify GTL templates, you need the information in this User's Guide, which helps you understand important concepts and offers many complete code examples illustrating often used features. You also need access to the SAS/GRAPH Graph Template Language Reference, which is the language dictionary for GTL.

Creating a graph using GTL is a two step process:

Define the structure of the graph using the GTL syntax in a STATGRAPH template that is specified on the TEMPLATE procedure. Compile and save this template.
Create the graph by running the SGRENDER procedure to associate the appropriate data with the template.

Defining the Graph Template

GTL uses a structured "building-block" approach to defining a graph. The syntax provides a set of layout, plot, and other statements to define the graph. ODS Graph and the Template to Generate It shows a graph of car profiles by horsepower and the syntax necessary to define the graph using GTL.

ODS Graph and the Template to Generate It

The template definition consists of the following parts:

A. The GTL syntax block from BEGINGRAPH to ENDGRAPH.

B. The title for the graph.

C. The LAYOUT OVERLAY block. The results of the statements in this block are overlaid in the graph.

D. A histogram of the horsepower variable.

E. A density plot of the horsepower variable.

Running the program in ODS Graph and the Template to Generate It creates the CARS template and saves it in an item store.

Creating the Graph

To create the graph in ODS Graph and the Template to Generate It, the SGRENDER procedure is run to associate the appropriate data set with the compiled template:

proc sgrender data=sashelp.cars template=cars; run;

In the template definition, the HORSEPOWER variable is used explicitly for the HISTOGRAM and DENSITYPLOT statements. The explicit reference in the template to a variable named HORSEPOWER requires that the data set have a numeric column named HORSEPOWER. Using Dynamics and Macro Variables to Make Flexible Templates shows you how to make the template more flexible.

The GTL syntax supports a variety of layout, plot, and other statements to create a wide range of graphs. Details on all these statements and options are covered in this User's Guide and in the SAS/GRAPH Graph Template Language Reference.

When GTL is Needed

The graphs that are created by the analytical procedures use predefined GTL templates. These templates are designed by SAS procedure writers and shipped with SAS. Every graph created by these procedures has a corresponding template stored in the SASHELP.TMPLMST item store. To customize these templates, you must develop a basic understanding of the GTL.
Often analysts need graphs of the data before an analysis can be started. Or, the results of a complex analysis involving multiple procedures or DATA steps need to be presented as graphs. Although many of these tasks can be accomplished using the SG Procedures, those procedures do not provide many of the advanced layout capabilities of GTL. To create such custom graphs, you must develop a basic understanding of the GTL.