How to create a scatter plot with marginal histograms in SAS

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.

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:

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:
  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 (click to enlarge):

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.

tags: Data Analysis, GTL, Statistical Graphics

3 Comments

  1. Renee Harper
    Posted May 20, 2011 at 9:50 am | Permalink

    Rick,
    I'm so glad to see you highlight this content. It is one of our greatest untapped gems. I have an upcoming meeting to discuss updates and more content, so keep an eye on this growing resource.

    -Renee

  2. J.S.F.
    Posted August 2, 2012 at 10:28 am | Permalink

    I am very new to SAS, so please pardon the simplicity of this question. Thanks to your clear instructions, I have successfully executed the code with my own data. Right now I have one scatter-histo-plot for all the data - students in 6-10th grade , but I would like to have separate plots for each grade. Is there a simple way to do this? Ideally I'd have one image with five separate plots. Thank you!

    • Posted August 3, 2012 at 6:34 am | Permalink

      Welcome to SAS! I think you want to use the BY statement. Almost every SAS procedure has a BY statement, including SGRENDER. If you have a variable called GRADE with the values 6,7,...,10, use PROC SORT to sort the data BY GRADE. Then in the SGRENDER procedure, include the statement
      BY GRADE;

      Since you are new, let me tell you about the SAS support communities. These are places for anyone to discuss "how do I do..." in SAS. There is a community for "SAS/GRAPH and ODS Graphics" that can help you with additional questions like this. There are also other forums on the DATA step, statistical procedures, and so forth. Enjoy!

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