Technology Tales

Generating PNG files in SAS using ODS Graphics

Recently, I had someone ask me how to create PNG files in SAS using ODS Graphics so I sought out the answer for them. Normally, the suggestion would have been to create RTF or PDF files instead but there was a specific need so a different approach was taken. Adding the something like following lines before an SGPLOT, SGPANEL or SGRENDER procedure does the needful:

ods listing gpath='E:\';
ods graphics / imagename="test" imagefmt=png;

Here, the ODS LISTING statement declares the destination for the desired graphics file while the ODS GRAPHICS statement defines the file name and type. In the above example, the file test.png would be created in the root of the E drive of a Windows machine. However, this also works with Linux or UNIX directory paths.

Changing the working directory in a SAS session

It appears that PROC SGPLOT and other statistical graphics procedures create image files even if you are creating RTF or PDF files. By default, these are PNG files but there are other possibilities. When working with PC SAS , I have seen them written to the current working directory and that could clutter up your folder structure, especially if they are unwanted.

Being unable to track down a setting that controls this behaviour, I resolved to find a way around it by sending the files to the SAS work directory so they are removed when a SAS session is ended. One option is to set the session’s working directory to be the SAS work one and that can be done in SAS code without needing to use the user interface. As a result, you get some automation.

The method is implicit though in that you need to use an X statement to tell the operating system to change folder for you. Here is the line of code that I have used:

x "cd %sysfunc(pathname(work))";

The X statement passes commands to an operating system’s command line and they are enclosed in quotes. %sysfunc then is a macro command that allows certain data step functions or call routines as well as some SCL functions to be executed. An example of the latter is pathname and this resolves library or file references and it is interrogating the location of the SAS work library here so it can be passed to the operating systems cd (change directory) command for processing. This method works on Windows and UNIX so Linux should be covered too, offering a certain amount of automation since you don’t have to specify the location of the SAS work library in every session due to the folder name changing all the while.

Of course, if someone were to tell me of another way to declare the location of the generated PNG files that works with RTF and PDF ODS destinations, then I would be all ears. Even direct output without image file creation would be even better. Until then though, the above will do nicely.

Creating waterfall plots in SAS using PROC GCHART

Recently, I needed to create a waterfall plot couldn’t use PROC SGPLOT since it was incompatible with publishing macros that use PROC GREPLAY on the platform that I was using; SGPLOT doesn’t generate plots in SAS catalogs but directly creates graphics files instead. Therefore, I decided that PROC GCHART needed to be given a go and it delivered what was needed .

The first step is to get the data into the required sort order:

proc sort data=temp;
by descending result;
run;

Then, it is time to add an ID variable for use in the plot’s X-axis (or midpoint axis in PROC GCHART) using an implied value retention to ensure that every record in the dataset had a unique identifier:

data temp;
set temp;
id+1;
run;

After that, axes have to be set up as needed. For instance, the X-axis (the axis2 statement below) needs to be just a line with no labels or tick marks on there and the Y-axis was fully set up with these, turning the label from vertical to horizontal as needed with the ANGLE option controlling the overall angle of the word(s) and the ROTATE option dealing with the letters, and a range declaration using the ORDER option.

axis1 label=none major=none minor=none value=none;
axis2 label=(rotate=0 angle=90 "Result") order=(-50 to 80 by 10);

With the axis statements declared, the GCHART procedure can be defined. Of this, the VBAR statement is the engine of the plot creation with the ID variable used for the midpoint axis and the result variable used as the summary variable for the Y-axis. The DISCRETE keyword is needed to produce a bar for every value of the ID variable or GCHART will bundle them by default. Next, references for the above axis statements (MAXIS option for midpoint axis and AXIS option for Y-axis) are added and the plot definition is complete. One thing that has to be remembered is that GCHART uses run group processing so a QUIT statement is needed at the end to close it at execution time. This feature has its uses and appears in other procedures too though SAS procedures generally are concluded by a RUN statement.

proc gchart data=temp;
vbar id / sumvar=result discrete axis=axis2 maxis=axis1;
run;
quit;