Tuesday, November 25, 2014

Strange SAS Error Message

I spent far too long trying to debug a strange error message in SAS. The solution ended up being aggravatingly simple, but arriving at the solution was not. So I wanted to share the problem and solution. (I discovered this issue using SAS 9.1.3.)

MPRINT(TRANSPOSE): proc datasets nolist;
SYMBOLGEN: Macro variable OUT resolves to lib.table_name
NOTE: Line generated by the invoked macro "TRANSPOSE".
161 modify &OUT; label &NEWVAR = "&NEWLBL"; quit;

MPRINT(TRANSPOSE): modify lib.table_name;
NOTE: Line generated by the macro variable "OUT".
161 lib.table_name
NOTE: Enter RUN; to continue or QUIT; to end the procedure.

SYMBOLGEN: Macro variable NEWVAR resolves to count
SYMBOLGEN: Macro variable NEWLBL resolves to count: prevalence
MPRINT(TRANSPOSE): label count = "count: prevalence";

ERROR 200-322: The symbol is not recognized and will be ignored.
ERROR 22-322: Expecting a name.

NOTE: Statements not processed because of errors noted above.
NOTE: The SAS System stopped processing this step because of errors.
NOTE: SAS set option OBS=0 and will continue to check statements. This may cause NOTE: No observations in data set.
NOTE: PROCEDURE DATASETS used (Total process time):
      real time 0.00 seconds
      cpu time 0.00 seconds

If you start looking where the error statements start and look down, you'll miss the true source of the error.

So for those not familiar with PROC DATASETS, one of the options on the PROC DATASETS statement is the LIBRARY= option. It defaults to WORK. So this PROC DATASETS is looking only in WORK for the dataset lib.table_name. Since "lib." is not a valid part of a table name (and just the table name), it's not parsing it correctly, resulting in an error.

The error seems to cause the SAS code parser to trip and read the rest of the code incorrectly, and it looks like the following step is where the error occurs. However, it's actually the earlier step ("modify &OUT" or the resolved code, "modify lib.table_name").

The lesson is twofold: 1) Don't try to use an output library with the table name (e.g., "lib.table_name") when the LIBRARY= option on PROC DATASETS is not used. 2) Don't write a macro where an output data set can be specified (e.g., OUT=) and use PROC DATASETS without checking whether the user specified an output library. Alternatively, don't use PROC DATASETS. (There are some advantages to PROC DATASETS, so don't throw the baby out with the bathwater!)

I wasted a lot of time on this since I thought the macro could handle any type of input/output specified, but apparently that is not true. The solution for me was to remove the "lib." from the OUT= argument to the macro ("&OUT"). Since PROC DATSETS was looking in work, it found it after I made this "correction".

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