Using the DATA Step Graphics Interface

To create graphics output using DSGI:

When you create or enhance graphs with DSGI, the DSGI graphics are displayed and stored as part of the graphics output. When you execute the DATA step, DSGI creates a catalog entry using the name from the GRAPH(“CLEAR”, . . . ) function.

DSGI uses the name DSGI if you have not specified a name with the GRAPH(“CLEAR”, . . . ) function. The catalog entry is stored in WORK.GSEG, unless you specify another catalog with the GSET(“CATALOG”, . . . ) function.

If you create another graph using a name that matches an existing catalog entry in the current catalog, DSGI uses the default naming conventions for the catalog entry. See About GRSEGs for a description of the conventions used to name catalog entries.

If you want to store your output in a permanent library or in a different temporary catalog, use the GSET(“CATALOG”, . . . ) function. This function enables you to specify the libref, and catalog name for the output catalog. Before you use the GSET(“CATALOG”, . . . ) function, assign a libref using the LIBNAME statement.

You can display DSGI graphics output stored in catalog entries multiple times, using the GREPLAY procedure or the GRAPH window.

The DSGI DATA step is usually not written to produce an output data set. Unlike data sets created by the Annotate facility, which contain observations for each graphics element drawn. DSGI does not usually create an observation for each graphics primitive. Only variables created in the DATA step are written to the output data set.

You can output as many observations to the data set as you want. To output these values, you must use the OUTPUT statement. You can also use any valid SAS DATA step statements in a DSGI DATA step. See SAS Data Set Options: Reference for information about the statements used in the DATA step.

Some SAS/GRAPH global statements can be used with DSGI programs. DSGI recognizes FOOTNOTE, GOPTIONS, and TITLE statements. When TITLE and FOOTNOTE statements are used, the output from DSGI statements is placed in the procedure output area. See How Graphics Elements Are Placed in the Graphics Output Area for an explanation of how space in graphics output is allocated to titles and footnotes.

Some DSGI functions override the graphics options. The following table lists the DSGI functions that directly override graphics options. For details about the graphics options, see Graphics Options and Device Parameters Dictionary.

The operating state of DSGI determines which functions and routines can be issued at any point in the DATA step. You can submit a function or routine only when the operating state is appropriate. Reference The DSGI Function and Routine Dictionaries for how functions and routines should be ordered within the operating states.

The operating states defined by DSGI are as follows:

Refer to The DSGI Function and Routine Dictionaries for information about the operating states from which a function or routine can be issued.

When DSGI draws graphics, it evaluates x and y coordinates in terms of the current window system, either a window that you have defined or the default window system. Unless you define and activate a different window, DSGI uses the default window system.

The default window system assigns two arbitrary systems of units to the x and y axes. The default window guarantees a range of 0 through 100 in one direction (usually the y direction) and at least 0 through 100 in the other (usually the x direction). The ranges depend on the dimensions of your device. You can use the GASK(“WINDOW”, . . . ) routine to determine the dimensions of your default window system.

You can define the x and y ranges to be any numeric range. For example, you can use − 1000 to +2000 on the x axis and 30 to 35 on the y axis. The units used are arbitrary.

When DSGI encounters an error in a program, it flags the statement in the SAS log and displays a description of the error. (To receive SAS System messages, GSET(“MESSAGE”, . . . ) must be ON.) The description provides you with an explanation of the error. The description might also provide a return code. If you get a return code, you can refer to Return Codes for DSGI Routines and Functions for a description of the error and why it might have occurred.

Some of the most common errors in DSGI programs are as follows: