Array-understand the code that check if customer touch Failure during 6 months

[Ronein]

Hello

For each customer ID there is information of score in 6 months.

I want to check for each customer if he/she touch score 11 (Score 11 meaning is failure).

This code is working perfect.

However ,I want to understand how it works.

As I see the new variable "Flag_Failure" remember the value that was before (IF it was 11 ).

May anyone explain please?

Data a;
input ID Score1 Score2 Score3 Score4 Score5 Score6;
cards;
1 2 2 2 2 2 3
2 8 8 11 11 11 10
3 7 6 7 7 8 8 
4 11 11 11 11 10 10
;
run;

Data b;
set a;
Flag_Failure=0;
array diag{6} Score1-Score6;
do i=1 to 6;
if diag{i} in (11)then Flag_Failure=1;
end;
Drop i;
Run;

[PeterClemmensen]

You are correct. The indicator variable i runs through the array and sets Flag_Failure to 1 if it encounters a 11 value. Simple as that. You may consider using the Whichn Function for a job like this though..

data b;
   set a;
   Flag_Failure = whichn(11, of score:) > 0;
run;

[Ronein]

I just don't understand how the code is working.

Let's look for example at  ID 2 that have scores 

8 8 11 11 11 10

diag{1}  is 8 so Flag_Failure=0

then diag{2}  is 8 so Flag_Failure=0

then diag{3}  is 11 so Flag_Failure=1

then diag{4}  is 11 so Flag_Failure=1

then diag{5}  is 11 so Flag_Failure=1

then diag{6}  is 11 so Flag_Failure=0

So why finally we get Flag_Failure=1???

[PeterClemmensen · Accepted solution]

Think of it this way: If the i'th element of the array is 11 then Flag_Failure=1. Else do not touch Flag_Failure. That means that Flag_Failure will be 1 if just one of the elements is equal to 11. SAS does not reinitialize the variable within the loop. You do that yourself before the loop with Flag_Failure=0. I added a few Put Statements to your code below, hopefully it will make more sense.

Data b;
    set a;
    Flag_Failure=0;
    array diag{6} Score1-Score6;

    put "Before Loop: " Flag_Failure=;

    do i=1 to 6;
        if diag{i} in (11) then Flag_Failure=1;
        
        put "Inside Loop: " (diag[i])(=)Flag_Failure=;

    end;

    put "After Loop: " Flag_Failure= //;

    Drop i;
Run;