Monday, January 31, 2011

Dark Secrets of %sysfunc

I've been using the %sysfunc for quite sometime now. I must say that its a pretty handy tool.. Especially when you would want to do some heavy wieght lifting in macros. However, one must be mindful of the following... (can I say shortcomings?? Naa.. not quite...)

Quoting fails in %sysfunc:

It is starkly visible when you try using intnx function in a macro. For example, you would want to build a month incrementor in a loop. You would do something like this:

%macro doit;
%let dt='01JAN2011'd;
%do i=1 %to 12;
%put mon=%sysfunc(month(%sysfunc(intnx('month',&dt,&i))));
%mend doit;


(Note: We usually do not need a semi-colon (;) after invoking a macro.. But habits die-hard. I'm trying my best to aviod it..)

The above code fails to run as expected. %sysfunc throws up tantrums saying:

WARNING: An argument to the function INTNX referenced by the %SYSFUNC or %QSYSFUNC macro function is out of range.

This is purely because the %sysfunc does not like the quotes around the month inside the intnx function. Just remove them and SAS becomes your ever-loyal-man Friday!

Some basic funnctions like put and input doesn't work!!

I was taken aback when i discovered this. (Ya.. I know... I know that i din do my documentation reading properly when i was asked to..)

When I submit this program inside a macro,

%put %sysfunc(put('31Jan2011'd,worddate.));

SAS slaps me with this error message:

ERROR: The PUT function referenced in the %SYSFUNC or %QSYSFUNC macro function is not found.

But this is unexpected... Now.. How on the earth am i supposed to do the type casting which is an integral part of my life (of course apart from my wife!!)

SAS says that you should be using putn, putc, inputn and inputc instead of the regular put/input functions for numeric/charater variables respectively. Wow.. Problem solved!!!The above code can now be written as:

%put %sysfunc(putn('31Jan2011'd,worddate.));

%Sysfunc can be used with a format specifyer (similar to the put function)

This was one of those 'learnings' I had from my SAS Advanced Certification perparation. %sysfunc could be used along with a format speicifer (thus avoiding the necessity to have put function).

The above function can be further reduced as given beow:

%put %sysfunc(today(),worddate.);

So much for now.. Please let me know your thoughts on this or if you have found anything more interesting to do with the %sysfunc

Saturday, January 29, 2011

Am back!!

Hey Guys... I know this blog was asleep for a month or so without any activity.. I owe it to my Advanced SAS Certification preparaion...

And I got Certified!!!!

Now that I'm back.. You can expect more posts on the new things that i found out while preparing for the certification!