Update indexing variable in the do loop

[Dinurik]

Hi SAS Users,

I have been trying to resolve this problem, but keep failing, therefore I would greatly appreciate any help. 

The data are binomial (whether a  participant has a condition (1) or not(0)). There are 20 repeated measurements corresponding to 20 visits:

cond1 cond2 .... cond20

0   0   ...   0

0   1 ...     0

1   0 .... 0

0    0  ... 1   

etc.

I need to create 20 variables based on cond1-cond20, so that if a person had a condition at visit 1 all visits after it would be marked as 1; if condition was present at visit 2, all visits after the second would be marked as 1, etc. 

cond_new1 cond_new2 cond_new 3 .... cond_new20

0   0  0 ... 0

0   1  1... 1

1  1  1...  1

0  0  0 ... 1

My current code is: 

data interim;
   set old;
   array old_cond(20) cond1 - cond20;
   array new_cond(20) new_cond1 - new_cond20;
    do i = 1 to 20;
    new_cond(i) = old_cond(i);
end; drop i;
run;

data want;
set have;
array old_cond(19) cond1 - cond19;
array new_cond(20) new_cond1 - new_cond20;
do i = 1 to 19;
do j = 1 to 19;
if old_cond(i) = 1 then new_aids(i+j) = 1;
end; end;
run;

And the error message says that the array subscript is out of range. 

I cannot find in any SAS resources how to update an indexing variable so that it moved from say visit 2 to visit 20 and changed the value from 0 to 1 until it reaches the last visit. I would be really grateful for any help. 

Thanks!

[PaigeMiller · Accepted solution]

If i=18 and j=18 then you have a subscript of i+j which is 36, which is out of range.

Since you didn't actually provide data, this is UNTESTED code

data want;
set have;
array cond(20) cond1 - cond20;

do i = 2 to 20;
    if cond(i-1)=1 then cond(i)=1;
end;
drop i;
run;

[Dinurik]

Thank you, PaigeMiller! I tried it on my data and it worked. 

[Reeza]

Way too complicated, this will change in place with your old variables. If you don't want that you could create a new array of all values easily. 

data want;
set have;

array cond(20);

index = whichn(1, of cond(*));

do i=index to dim(cond);
cond(i) = 1;
end;

run;

---

@Dinurik wrote:

Hi SAS Users,

I have been trying to resolve this problem, but keep failing, therefore I would greatly appreciate any help. 

The data are binomial (whether a  participant has a condition (1) or not(0)). There are 20 repeated measurements corresponding to 20 visits:

cond1 cond2 .... cond20

0   0   ...   0

0   1 ...     0

1   0 .... 0

0    0  ... 1   

etc.

I need to create 20 variables based on cond1-cond20, so that if a person had a condition at visit 1 all visits after it would be marked as 1; if condition was present at visit 2, all visits after the second would be marked as 1, etc. 

cond_new1 cond_new2 cond_new 3 .... cond_new20

0   0  0 ... 0

0   1  1... 1

1  1  1...  1

0  0  0 ... 1

My current code is: 

data interim;
   set old;
   array old_cond(20) cond1 - cond20;
   array new_cond(20) new_cond1 - new_cond20;
    do i = 1 to 20;
    new_cond(i) = old_cond(i);
end; drop i;
run;

data want;
set have;
array old_cond(19) cond1 - cond19;
array new_cond(20) new_cond1 - new_cond20;
do i = 1 to 19;
do j = 1 to 19;
if old_cond(i) = 1 then new_aids(i+j) = 1;
end; end;
run;

And the error message says that the array subscript is out of range. 

I cannot find in any SAS resources how to update an indexing variable so that it moved from say visit 2 to visit 20 and changed the value from 0 to 1 until it reaches the last visit. I would be really grateful for any help. 

Thanks!

---

[Dinurik]

I tried it on my data and it didn't work. SAS says:  Array subscript out of range at line "cond(i) = 1;"

[Reeza]

Is it possible to not have a 1 in any row? Otherwise that should work given your problem statement. You can add an IF condition to enter the loop only if the index is between 1 and 20.