Re: st: Evaluate if a dataset is empty

[Maarten Buis <maartenlbuis@gmail.com>]

On Thu, Mar 27, 2014 at 11:51 AM, Seliger  Florian wrote:
> I want Stata to go through 20,000 small datasets (with a forvalues loop, datasets are indexed accordingly) and evaluate if the dataset is empty or not. About 50% of the datasets are empty meaning that there are no values for any variable.

capture assert _N == 0
if _rc == 0 {
    set obs 18
    ...
}

The logic is that _N is the number of observations in the dataset, so
_N == 0 corresponds to an empty dataset. -assert- gives an error
message when the statement is values, but -capture- captures these
error messages and leaves the return code behind in _rc. No error
message corresponds with an return code 0, so _rc == 0 corresponds
with an empty dataset.

Hope this helps,
Maarten

---------------------------------
Maarten L. Buis
WZB
Reichpietschufer 50
10785 Berlin
Germany

http://www.maartenbuis.nl
---------------------------------
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