Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: st: Evaluate if a dataset is empty
From
Alfonso Sanchez-Penalver <[email protected]>
To
"[email protected]" <[email protected]>
Subject
Re: st: Evaluate if a dataset is empty
Date
Thu, 27 Mar 2014 07:04:49 -0400
I may be missing something here but if a dataset is empty wouldn't _N=0?
Alfonso Sanchez-Penalver
> On Mar 27, 2014, at 6:51 AM, "Seliger Florian" <[email protected]> wrote:
>
> Dear Statalist
>
> 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.
> Please note that the variables are the same across all datasets.
>
> For empty datasets, Stata is asked to create observations, to generate an identifier and to set all values equal to zero (except for the identifier):
>
> set obs 18
> bys id: replace id=_n
>
> forvalues k=1(1)18 {
> replace ind `k'=0 if ind`k'==.
> }
>
>
> At the end, I want to merge datasets based on "id". It is important that empty datasets are included and contain zeros.
>
>
> My problem is that I do not know how to ask STATA to evaluate whether a dataset is empty or not.
> Before "set obs 18" STATA does not recognize that values are missing meaning that there is simply "nothing" in the dataset.
> How can I ask STATA to identify that there is "nothing" within my loop (forvalues i=1(1).)?
>
> Thanks a lot,
> Florian
>
>
>
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/faqs/resources/statalist-faq/
> * http://www.ats.ucla.edu/stat/stata/
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/faqs/resources/statalist-faq/
* http://www.ats.ucla.edu/stat/stata/