Re: st: conditional "keep" statement

[David Souther <davidsoutheremail@gmail.com>]

.Many thanks to Eric Booth, Robert Picard, + David Kantor for the
help.  I found that Robert's approach worked for me given my large
num. of variables.   D.S.


On Mon, Apr 12, 2010 at 10:07 AM, David Kantor <kantor.d@att.net> wrote:
> At 09:54 AM 4/12/2010, David Souther wrote:
>>
>> I'm combining (append & merge) hundreds of files which contain
>> hundreds or thousands of variables each, and at each stage of the
>> merge/append, I'd like to variables only if they are in a list that I
>> specify.
>> The issue is that not all of these datasets contain all the variables
>> in this list.  So, if I create a macro of my list,
>>
>> local myvars  a1 a2 a3 d1 d2 d3
>>
>> and then specify,
>>
>> keep `myvars'
>>
>> in the loop for each combination of data, I get the error that some
>> variable doesn't exist when it's not in the dataset.  I tried getting
>> around this with the -capture- command,
>>
>> cap keep `myvars'
>>
>> and using -ds-
>>
>> ds `myvars'
>> keep `r(varlist)'
>>
>> or,
>>
>> ds `myvars', not
>> drop `r(varlist)'
>>
>> and -ds- in combination with -capture- to no avail.   Any other ideas
>> (besides specifying the hundreds of variables to keep for each/every
>> loop)??
>> [...]
>
> Hi.
> I'm not sure what to do if you bump into limits of macros, but I wonder if
> you know about macrolists. This may be useful.
>
> local myvars  a1 a2 a3 d1 d2 d3
> ds
> localdatasetvars "`r(varlist)'"
> local commonvars : list myvars & localdatasetvars
>
> commonvars now contains the variable names common to the dataset and to
> myvars.
>
> See -help macrolists-.
>
> HTH
> --David
>
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/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/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/