topic Re: Who do I "concatenate" missing visit data? in SAS Programming

Who do I "concatenate" missing visit data?

nyitray — Thu, 19 Jul 2012 22:13:23 GMT

I’m doing analysis on a longitudinal study with up to 10 visits for some participants. Some data are missing. If data for a participant are not missing at a subsequent visit, then that subsequent visit data needs to replace the prior missing data. For example, participant A might have missed visit 1 but attended visits 2 through 10. I need the nonmissing data in vists 2-10 to concatenate left (or ‘shift’ to the left) so there are nonmissing data in vists 1-9 and one missing datum in visit 10. Of course, missing data could occur at any visit. All variable names have a suffix identifying visit number. Below is an example using numeric data (for example, positive or negative blood tests at each of ten visits); however, variables could be character or numeric. All help on this is appreciated - I wonder now if converting this wide data to long form is the first step...

Data Have

Obs x_v1 x_v2 x_v3 x_v4 x_v5 x_v6 x_v7 x_v8 x_v9 x_v10

1 . 1 0 1 0 1 0 1 0 1

2 0 . 1 0 0 . . 1 0 0

3 . 1 0 1 0 1 0 1 0 .

Data Want

Obs x_v1 x_v2 x_v3 x_v4 x_v5 x_v6 x_v7 x_v8 x_v9 x_v10

1 1 0 1 0 1 0 1 0 1 .

2 0 1 0 0 1 0 0 . . .

3 1 0 1 0 1 0 1 0 . .

Re: Who do I "concatenate" missing visit data?

Linlin — Thu, 19 Jul 2012 23:21:37 GMT

data have;

input id x_v1 x_v2 x_v3 x_v4 x_v5 x_v6 x_v7 x_v8 x_v9 x_v10;

cards;

1 . 1 0 1 0 1 0 1 0 1

2 0 . 1 0 0 . . 1 0 0

3 . 1 0 1 0 1 0 1 0 .

;

data long(keep=id v);

set have;

array x(*) x_v1-x_v10;

do _n_=1 to dim(x);

v=x(_n_);

if not missing(v) then output;

end;

run;

data want(drop=v count);

retain x_v1-x_v10;

array x x_v1-x_v10;

set long;

by id notsorted;

if first.id then count=0;

count+1;

x(count)=v;

if last.id then do;

output;

call missing (of x(*));

end;

run;

proc print;run;

Linlin

Re: Who do I "concatenate" missing visit data?

nyitray — Fri, 20 Jul 2012 00:18:39 GMT

Thanks Linlin! This worked quite well. Alan

Re: Who do I "concatenate" missing visit data?

Haikuo — Fri, 20 Jul 2012 03:18:33 GMT

Or you can try this:

data have;

input id x_v1 x_v2 x_v3 x_v4 x_v5 x_v6 x_v7 x_v8 x_v9 x_v10;

cards;

1 . 1 0 1 0 1 0 1 0 1

2 0 . 1 0 0 . . 1 0 0

3 . 1 0 1 0 1 0 1 0 .

;

data want (drop=_:);

set have;

length _t $50.;

array old x_v1-x_v10;

_t=catx(' ',of old(*));

_n=n(of old(*));

call missing(of old(*));

do _n_=1 to _n;

old(_n_)=scan(_t,_n_);

end;

run;

proc print;run;

Haikuo