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Here is a DATA step solution.
First step: create two datasets, one (A) with the original data plus a
sequence number (OBSNUM), the other with an indicator to mark points where
a sequence starts or ends:
data a(keep = obsnum a)
b(keep = obsnum b);
set whatever;
obsnum = _n_;
output a;
if a ne lag(a)+1 then do;
b = 0;
output b;
count = 0;
end;
count ++ 1;
if count=7 then do;
obsnum = _n_ - 7 + 1;
b = 1;
output b;
end;
run;
Second step: combine the two and propagate the B values:
data result;
update a b;
by obsnum;
drop obsnum b;
rename bb = b;
if b ne . then bb = b;
retain bb;
run;
I used UPDATE rather than MERGE because it handles one-to-many cases
appropriately.
On Wed, 19 Mar 2003 17:32:31 -0500, Primak, Philip
<Philip.Primak@GENZYME.COM> wrote:
>Dear SAS-L
>
>I have the following problem:
>There is a data set with some numeric variable (let's say A)
> Obs A
>
> 1 .
> 2 1
> 3 2
> 4 2
> 5 3
> 6 4
> 7 5
> 8 6
> 9 7
> 10 8
> 11 8
> 12 9
> 13 99
>
>I have to distinguish those observations, where A is consequent 7 numbers.
>Another words I need to create variable B, which will be equal to 1 for
>observations 4-10 and 0 otherwise.
>
>Any help is appreciated.
>
>thanks
>Philip Primak
>Genzyme Corp
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