WARNING: No bars were drawn. This could have been caused by ORDER= on the AXIS statement. You might wish to use the MIDPOINTS= option on the VBAR statement instead.

What you see above is a an error issued by a SAS program like what a colleague at work recently found. The following code will reproduce this so let us walk through the steps to explain a possible cause for this.

The first stage is to create a test dataset containing variables y and x, for the vertical and midpoint axes, respectively, and populating these using a CARDS statement in a data step:

data a;
input y x;
cards;
1 5
3 9
;
run;

Now, we define an axis with tick marks for particular values that will be used as the definition for the midpoint or horizontal axis of the chart:

axis1 order=(1 3);

Then, we try creating the chart using the GCHART procedure that comes with SAS/GRAPH and this is what results in the error message being issued in the program log:

proc gchart data=a;
vbar x / freq=y maxis=axis1;
run;
quit;

The cause is that the midpoint axis tick marks are no included in the data so changing these to the actual values of the x variable removes the message and allows the creation of the required chart. Thus, the AXIS1 statement needs to become the following:

axis1 order=(5 9);

Another solution is to remove the MAXIS option from the VBAR statement and let GCHART be data driven. However, if requirements do not allow this, create a shell dataset with all expected values for the midpoint axis with y set 0 since that is used for presenting frequencies as per the FREQ option in the VBAR statement.

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.

Some SAS Macro code for detecting the presence or absence of a variable in a dataset

Recently, I needed to put in place some code to detect the presence or absence of a variable in a dataset and I chose SAS Macro programming as the way to do what I wanted. The logic was based on a SAS sample that achieved the same result in a data step and some code that I had for detecting the presence or absence of a dataset. Mixing the two together gave me something like the following:

%macro testvar(ds=,var=);

%let dsid=%sysfunc(open(&ds,in));
%let varexist=%sysfunc(varnum(&dsid,&var));
%if &dsid > 0 %then %let rc=%sysfunc(close(&dsid));

%if &varexist gt 0 %then %put Info: Variable &var is in the &ds  dataset;
%else %put Info: Variable &var is not in the &ds  dataset;

%mend testvar;

%testvar(ds=dataset,var=var);

What this does is open up a dataset and look for the variable number in the dataset. In datasets, variables are numbered from left to right with 1 for the first one, 2 for the second and so on. If the variable is not in the dataset, the result is 0 so you know that it is not there. All of this is what the VARNUM SCL function within the SYSFUNC macro function does. In the example, this resolves to %sysfunc(varnum(&dsid,var)) with no quotes around the variable name like you would do in data step programming. Once you have the variable number or 0, then you can put in place some conditional logic that makes use of the information like what you see in the above simple example. Of course, that would be expanded to something more useful in real life but I hope it helps to show you the possibilities here.

Presenting more than one plot on a page using SAS ODS PDF

If you had asked me about getting two or more graphs on a page using SAS/GRAPH procedures, I might have suggested PROC GREPLAY as the means to achieve it. However, I recently came across another way to do the same thing by using ODS. It helped that the graphs were being produced using the PDF destination because I don’t think that what follows will work with the RTF one.

For this three plots on a page example, I first set the orientation to landscape so that the plots can be arranged side by side in a single row:

options orientation=landscape;

Next, the PDF destination was opened with page breaks turned off for the required output file using the STARTPAGE option:

ods pdf file=”c:\test.pdf” startpage=off;

The listing destination was turned off as well since it is not needed:

ods listing close;

With that complete, a page or region break gets inserted. This could have been repeated before every procedure to get it popped into the next region on the page but that is the default behaviour for any extra procedural step so it wasn’t needed.

ods pdf startpage=now;

Then, the ODS LAYOUT feature is started so that the layout can be defined on the page:

ods layout start;

For the first plot and the one at the left of the triptych, a region was defined absolutely (grid layouts are available but I didn’t make use of them here) using ODS REGION. Since all plots were to be of the same size, the width was defined as being a third of the page and the bottom left hand corner of the region defined to be the same as that of the plot area on the page. Titles and footnotes usefully lie outside this region in the way that SAS arranges things so there is no further messing. With the region define, it’s a matter of running the required SAS/GRAPH procedure. In my case, this was GPLOT but I am certain that others would work as well. The height was defined as the full possible plot height. This could have a use if I wanted more than one row of graphs on a page with a trellis plot being an example of that sort of arrangement.

ods region x=0pct y=0pct width=33pct height=100pct;

<< SAS/GRAPH Procedure >>

For the middle plot, the starting position is moved a third of the way along the page while the section area has the same dimensions as before. Using percentages in these definitions does make their usage easier.

ods region x=33pct y=0pct width=33pct height=100pct;

<< SAS/GRAPH Procedure >>

Lastly, the right-hand plot has a starting position two-thirds of the width of the page and the other dimensions are as per the other panels:

ods region x=66pct y=0pct width=33pct height=100pct;

<< SAS/GRAPH Procedure >>

With the last graph created, it is time to close ODS LAYOUT and the PDF destination. Then, the listing destination is reopened again.

ods layout end;
ods pdf close;
ods listing;

Update 2012-12-08: Since writing the above, I have learned that ODS LAYOUT and ODS REGION have yet to become production features of SAS with 9.3 as the latest version. However, I have encountered an alternative that uses the STARTPAGE=NEVER ODS PDF option to turn off page breaks and GOPTIONS statements to control the regions occupied by plots. It’s Sample 48569 on the SAS website. Having a production equivalent is better since pre-production features are best avoided in production code. If I had realised the status, I would have used PROC GREPLAY to achieve what I needed to do.

Using the IN operator in SAS Macro programming

This useful addition came in SAS 9.2 and I am amazed that it isn’t enabled by default. To do that you need to set the MINOPERATOR option unless someone has done it for you in the SAS AUTOEXEC or another configuration program. Thus, the safety first approach is have code like the following:

options minoperator;

%macro inop(x);

%if &x in (a b c) %then %do;
%put Value is included;
%end;
%else %do;
%put Value not included;
%end;

%mend inop;

%inop(a);

Also, the default delimiter is the space so if you need to change that, then the MINDELIMTER option needs setting. Adjusting the above code so that the delimiter now is the comma character gives us the following:

options minoperator mindelimiter=”,”;

%macro inop(x);

%if &x in (a,b,c) %then %do;
%put Value is included;
%end;
%else %do;
%put Value not included;
%end;

%mend inop;

%inop(a);

Without any of the above, the only approach is  to have the following and that is what we had to do for SAS versions prior to 9.2:

%macro inop(x);

%if &x=a or &x=b or &x=c %then %do;
%put Value is included;
%end;
%else %do;
%put Value not included;
%end;

%mend inop;

%inop(a);

It may be clunky but it does work and remains a fallback in newer versions of SAS. Saying that, having the IN operator available makes writing SAS Macro code that little bit swisher so it’s a good thing to know.