st: If-condition for running syntax

[Jörg Eulenberger <j.eulenberger@web.de>]

Dear Statalisters,
i want to produce many different outputs with a loop over a categorical
variable (30 subsets). Now i have a problem with same variables.
In some subsets one variable have positive values, in some subsets is
this not the case.
When i run the loop, Stata produce a error by subset 6:

width() invalid -- invalid number, outside of allowed range
r(125);

end of do-file

r(125);

To resolve the problem, i think the following way are possible (right?):

if  /var have min one case with value/ ==1 {
tab var
}
else {
    display as text "no output "
}


Know everyone the right syntax to express : "/variable have min one case
with value==1"/
Thanks,
Jörg
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