topic Re: CPU Time to be Processed in SAS Programming

CPU Time to be Processed

Sudtej — Sun, 15 Jun 2014 06:34:21 GMT

The SAS data set TEMP has the following distribution of values for variable A:

A Frequency

1 500,000

2 500,000

6 7,000,000

8 3,000

Which one of the following SAS programs requires the least CPU time to be processed?

A. data new; set temp; if a = 8 then b = 'Small '; else if a in(1, 2) then b = 'Medium'; else if a = 6 then b = 'Large'; run;

B. data new; set temp; if a in (1, 2) then b = 'Medium'; else if a = 8 then b = 'Small'; else if a = 6 then b = 'Large'; run;

C. data new; set temp; if a = 6 then b = 'Large '; else if a in (1, 2) then b = 'Medium'; else if a = 8 then b = 'Small';run;

D. data new; set temp; if a = 6 then b = 'Large '; if a in (1, 2) then b = 'Small'; run;

Note: The above question is from Advance sas practice exam which i found online. i would like to know the correct answer and why?

Thank you.

Re: CPU Time to be Processed

LinusH — Sun, 15 Jun 2014 12:38:01 GMT

If SAS hits a TRUE, the rest of the if-then-else logic is not executed.

Therefore, one should organize the code, so that the most likely expression to be TRUE, is to be evaluated first.

Re: CPU Time to be Processed

Reeza — Mon, 16 Jun 2014 03:41:57 GMT

You should order your conditions in the order they occur in the data set, most frequent to less frequent. Also, if conditions are mutually exclusive use the if then is faster than multiple if as in D.