## why " if _n_ =1 or _n_=last;" works but " if _n_ in (1, last);" doesn't?

Super Contributor
Posts: 1,636

# why " if _n_ =1 or _n_=last;" works but " if _n_ in (1, last);" doesn't?

Thank you very mush for your inouts!

data good; /**/
set sashelp.class nobs=last;
if _n_ =1 or _n_=last;
proc print data=good;run;

set sashelp.class nobs=last;
if _n_ in (1, last);

Posts: 5,535

## Re: why " if _n_ =1 or _n_=last;" works but " if _n_ in (1, last);" doesn't?

There is a proposition by Chris@NewZealand to provide the ability to use variable names with the IN operator, see

https://communities.sas.com/ideas/1356

PG

PG
Super Contributor
Posts: 339

## Re: why " if _n_ =1 or _n_=last;" works but " if _n_ in (1, last);" doesn't?

from In Operator documentation in SAS

The IN operator compares a value produced by an expression on the left side of the operator to a list of values on the right.

from nobs= option documentation in SAS

creates and names a temporary variable whose value is usually the total number of observations in the input data set or data sets.

So the issue is simply that the IN operator only supports value list and not variables. The following will cause an error

data _null_;

a=1; b=2;

if a in (a,b) then put "hello world!";

run;

for the exact same reason that the IN operator does not support variables.

Vincent

Posts: 3,852

## Re: why " if _n_ =1 or _n_=last;" works but " if _n_ in (1, last);" doesn't?

set sashelp.class nobs=last;
array _x
• _1 last (
• 1 0);
if _n_ in _x;
drop _:;
run;

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