Many people know that the SGPLOT procedure in SAS 9.2 can create a large number of interesting graphs. Some people also know how to create a panel of graphs (all of the same type) by using the SGPANEL procedure. But did you know that you can also create a panel of graphs of different types in SAS by writing a template that describes how to layout each plot within the panel? Even better, there is a gallery of pre-written templates so that for many situations you don't have to write (or even understand) the Graph Template Language (GTL). You can simply copy a pre-written template!

This blog post shows how to create a scatter plot with marginal histograms in SAS by copying a pre-written template. You can download the SAS program and use the template in your own work.

Galleries of Statistical Graphics

When I want to create a plot that is somewhat complicated, the first thing I do is to look in the SAS/GRAPH Graphics Gallery. In particular, I use the galleries for the ODS Statistical Graphics (SG) procedures:

• Graphics gallery for the SGPLOT procedure: create one plot
• Graphics gallery for the SGPANEL procedure: create a panel of plots, each of the same plot type
• Graphics gallery for the SGRENDER procedure: use with the GTL to layout multiple plots of different types, or to produce nonstandard plots
• Graphics gallery for the SGSCATTER procedure: create a panel of scatter plots

The graph that I want to produce is in the PROC SGRENDER gallery (Sample 35172), which links to a SAS Knowledge Base article on how to use the Graph Template Language (GTL) to produce a distribution plot.

How to Create a Scatter Plot with Marginal Histograms

Using the SAS Knowledge Base article as a guide, the following steps create a scatter plot with marginal histograms (download the program):

1. Click on the Full Code tab to display the SAS program that generates the graph.
2. Copy the first call to the TEMPLATE procedure into your SAS session:

   proc template; define statgraph scatterhist; ... run;

3. Modify the example code, if necessary, to fit your needs. For example, I made the following changes:
   • I don't want transparent markers for my scatter plot, so I set datatransparency=0 on the SCATTERPLOT statement. (You can use transparency to help deal with overplotting in scatter plots.) Optionally, you can use a parameter to specify at run time whether to use semi-transparent markers.
   • I don't want the text "NOBS = number of points" to appear in the upper right portion of the plot, so I replace that text with an empty string.
4. Run the PROC TEMPLATE code to create the template.
5. Copy the PROC SGRENDER code at the end of the program and modify it to run on your data. For example, the following statements call PROC SGRENDER to produce a scatter plot with marginal histograms on the Height and Weight variables in the SasHelp.Class data set:

   /** create panel of plots using the ScatterHist template **/ ods graphics; proc sgrender data=SasHelp.Class template=scatterhist; dynamic YVAR="Weight" XVAR="Height" TITLE="Height-Weight Relationship"; run;

The SGRENDER procedure uses the ScatterHist template to layout the scatter plot and histograms, as shown below:

In this example, I modified the GTL template in a minor way, but I also could have used the template as it is. You can learn more about the Graph Template Language if you decide to modify templates or to write your own templates. I also recommend the book Statistical Graphics in SAS: An Introduction to the Graph Template Language and the Statistical Graphics Procedures by my colleague, Warren Kuhfeld.