Arrays... when are they better than just a do loop?

[ManitobaMoose]

Hi,

Are there any resources regarding when to do a do loop with an array, as opposed to just a do loop without an array? What are the advantages of using an array, and when use them?

Thanks.

[PaigeMiller · Accepted solution]

ARRAYs are usually useful when you want to perform the same (or very similar) analysis on many different columns.

Do loops not in an array are much more general, and allow you to iterate until some (hopefully) desirable result is obtained.

[ManitobaMoose]

Thanks.

I also have one other related question: the _n_ = 1 for arrays. Does that mean it starts at the first observation, first line. etc? I see that written and I am not entirely sure what it does. See the code below.

Data score ; 
	array ans{10} $1 ; 
	array key{10} $1 _temporary_  ; 
*Load the temporary array elements*
	If _n_ = 1 then do Ques = 1 to 10 ; *_n_ = 1 only does first line of the key *
I		input key{Ques} $1. @ ; 
	end ; 
	
	Input ID (Ans1-Ans10) ($1.) ;
	Rawscore = 0 ; 
	
*Score the Test*
	do Ques = 1 to 10 ; 
		Rawscore + (key(Ques) eq Ans(Ques)) ; 
	end ; 
Percent = 100*Rawscore ; 
keep ID Rawscore Percent ; 
Datalines ;