topic Update indexing variable in the do loop in SAS Programming

Update indexing variable in the do loop

Dinurik — Thu, 13 Jun 2019 16:40:26 GMT

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!

Re: Update indexing variable in the do loop

PaigeMiller — Thu, 13 Jun 2019 16:48:23 GMT

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;

Re: Update indexing variable in the do loop

Reeza — Thu, 13 Jun 2019 16:51:20 GMT

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!

Re: Update indexing variable in the do loop

Dinurik — Thu, 13 Jun 2019 17:01:29 GMT

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

Re: Update indexing variable in the do loop

Dinurik — Thu, 13 Jun 2019 17:11:24 GMT

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

Re: Update indexing variable in the do loop

Reeza — Thu, 13 Jun 2019 17:19:12 GMT

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.