topic Re: Efficient Program in SAS Programming

Efficient Program

sam_sas2 — Mon, 15 Feb 2021 18:31:36 GMT

Hi All!

Assume a variable binary which has values- 0 and 1.

Which piece of code will be more efficient and why?

1. CODE-1

if binary=1 then output;

2. CODE-2

if binary then output;

Thanks in advance! 🙂

Re: Efficient Program

SASKiwi — Mon, 15 Feb 2021 19:21:18 GMT

No difference except you save a little bit of typing in the second example.

Re: Efficient Program

Astounding — Mon, 15 Feb 2021 21:13:13 GMT

CODE 2 will be slightly more efficient. But you probably can't measure the difference without billions of observations.

CODE 1 has an extra step: determine whether BINARY is equal to 1 or not. Replace true comparisons with 1 and false comparisons with 0. Then determine whether the result is true or false (1 will be true, and 0 will be false.)

CODE 2 skips a very, very tiny step. It determines whether BINARY is true or false. (Again, 1 is true and 0 is false.) So that's one less step. One very, very tiny step.

If BINARY were able to take on values other than 0 or 1, the answer becomes a bit more complex.

Re: Efficient Program

sam_sas2 — Tue, 16 Feb 2021 07:22:06 GMT

Hey! Thanks for the explanation. For arguments sake, let us assume the variable BINARY can take values from 0 to 9. Then how does it work?

Thanks in advance! 🙂

Re: Efficient Program

Kurt_Bremser — Tue, 16 Feb 2021 08:51:37 GMT

@sam_sas2 wrote:
Hey! Thanks for the explanation. For arguments sake, let us assume the variable BINARY can take values from 0 to 9. Then how does it work?

Thanks in advance! 🙂

It then depends which of those values are considered "true" and which ones "false".

Re: Efficient Program

ballardw — Tue, 16 Feb 2021 09:21:29 GMT

@sam_sas2 wrote:
Hey! Thanks for the explanation. For arguments sake, let us assume the variable BINARY can take values from 0 to 9. Then how does it work?

Thanks in advance! 🙂

How are you using those values?

If you mean to try:

if value then output;

Then everything except 0 would be output. (0 is false, the other values would be treated as "true").

But if want to do something different with different values, or groups of values, then it depends what you want to do conditionally.

Read the documentation on SELECT/WHEN or IF/THEN/ELSE as starters.

Re: Efficient Program

Ksharp — Tue, 16 Feb 2021 11:55:06 GMT

As Astounding , my guess is also second one .

Re: Efficient Program

sam_sas2 — Tue, 16 Feb 2021 14:54:42 GMT

Yes. I got that! Now I just want to understand in terms of efficiency when I run the program with syntax
IF <variable> then output vs IF <variable>= x then output
assuming both would give me the same output.
Hope my question is clear! 🙂