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Re: st: e(wexp) versus e(wexp): different routines return different things


From   Stas Kolenikov <skolenik@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: e(wexp) versus e(wexp): different routines return different things
Date   Sat, 27 Aug 2011 16:51:41 -0500

Nick,

the original poster had an issue of some commands returning -e(wexp)-
with an equal sign, and others, without it. So the equal sign had to
be parsed out.

On Sat, Aug 27, 2011 at 2:44 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> Too complicated :)
>
>  tempvar wvar
>  if "`e(wexp)'" == "" generate byte `wvar' = 1
> else generate double `wvar' `e(wexp)'
>
> On Sat, Aug 27, 2011 at 8:28 PM, Stas Kolenikov <skolenik@gmail.com> wrote:
>> Oh those overqualified programmers working in Stata :). Regular
>> expressions are an overkill for situation like this. You can achieve
>> what you need with the string functions.
>>
>> tempvar wvar
>> if "`e(wexp)'" == "" generate byte `wvar' = 1
>> else {
>>  local mywexp = subsinstr("`e(wexp)'","=","",1)
>>  generate double `wvar' = `mywexp'
>> }
>>
>> and then you can pass `wvar'.
>>
>> On Fri, Aug 26, 2011 at 8:49 PM, Rodini, Mark
>> <mrodini@compasslexecon.com> wrote:
>>> Greetings,
>>>
>>> I have a program which executes after I run an estimation procedure, and it does a collapse where weighting is an option.
>>> Within the program is the following line:
>>>
>>>
>>> if "`e(wexp)'" != "" {
>>>                        collapse (mean) `y_sample' `xb_sample' [fw `e(wexp)']
>>>                }
>>>
>>> I'm running an estimation using "reg" and one using "newey2".  Suppose the name of the weighting variable, should I opt to use it, is "mycount" so for example, I run:
>>>
>>> reg y high low cows [aw=mycount]
>>>
>>> and then execute the program.
>>>
>>>
>>> Both estimation routines create as output an estimation "variable" called e(wexp).  Note that this is what is passed to the program as indicated above.
>>>
>>> Here is the kicker: reg returns e(wexp) as "= mycount", but newey2 returns e(wexp) as "mycount" (without the equals sign!)
>>>
>>> The reg version properly executes the program above, but newey2 gives an error about an inability to weight, since the syntax requires an equals sign.
>>>
>>> I have tried within the program to create a tempname or tempvar, assign e(wexp) to it and then tried running
>>>
>>> scalar `wts'=regexr(`e(wexp)',"=","")
>>>
>>> I then replace the `e(wexp)' in the program with `wts' and add an equals sign explicitly in the program.  The idea I was hoping for is that it would replace the "=" with nothing in the macro variable, if one were there.
>>>
>>> No matter how I try it, it fails, usually with a type mismatch error.  I tried adding double quotes, etc.  I am assuming that because I'm trying to pass it as a scalar, that is what bombs it.  Any thoughts?  I'm guessing it's something pretty basic --I'm kind of new to writing complicated programs which pass lots of stuff.
>>
>>
>>
>> --
>> Stas Kolenikov, also found at http://stas.kolenikov.name
>> Small print: I use this email account for mailing lists only.
>>
>> *
>> *   For searches and help try:
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>> *   http://www.ats.ucla.edu/stat/stata/
>>
>
> *
> *   For searches and help try:
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> *   http://www.ats.ucla.edu/stat/stata/
>



-- 
Stas Kolenikov, also found at http://stas.kolenikov.name
Small print: I use this email account for mailing lists only.

*
*   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/


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