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Re: st: Maximum length of a string expression in a program


From   Eva Poen <eva.poen@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Maximum length of a string expression in a program
Date   Mon, 16 Mar 2009 14:00:17 +0000

Davide,

I think you can use the macro list commands for your problem, see
-help macrolists-. However, wouldn't it be easier to just define a
constraint and apply it to the regression? Like

forvalues k=1/`=`nr'' {
  local thisreg : word `k' of `regressors'
  constraint define `k' `thisreg'=0
}

Then you can call your regression command with the constraint option ,
e.g. regress `depvar' `regressors', constraint(1)

Eva


2009/3/16 Davide Cantoni <davide.cantoni@gmail.com>:
> Dear Maarten, Eva,
>
> thanks for your suggestions. So I found out that, as you pointed out,
> the problem in my file is not the line containing
>
> `command' `depvar' `regressors' `if'  [`weight' `exp'] , `options'
>
> But rather two other lines:
>
> ***
> local regressors=trim("`regressors'")
> ***
>
> and
>
> ***
> local nr=wordcount("`regressors'")
> foreach k of numlist 1(1)`nr' {
>     ...
>     local regrs_no``k'' = subinword("`regressors'","``k''","",.)
>     ...
> }
> ***
>
> I do not have instances in my code where I evaluate the string with an
> = sign. But these two lines seem to be the stumbling stone. The first
> one is just for cosmetic reasons, and I can merrily dispense with it.
> In the other case the stumbling stone is -subinword-, not -wordcount-.
> What I am doing there is eliminating one of the regressors at a time
> (in order to run the regression with the imposed "null hypothesis" of
> the corresponding beta to be zero). But Stata does not seem to like
> subinword when the list is too long. What can I do there so get around
> this problem?
>
> Thanks again,
>
> Davide
>
> On Mon, Mar 16, 2009 at 5:10 AM, Maarten buis <maartenbuis@yahoo.co.uk> wrote:
>>
>> --- On Mon, 16/3/09, Davide Cantoni wrote:
>>> I have a question related to programming a new program/ado
>>> file. I am encountering the problem that one of the
>>> arguments of my program might be too long as a string,
>>> going beyond the limit of 244 characters.
>> <snip>
>>> I am encountering problems when running -mycommand- with a
>>> list of regressors that is longer than 244 characters.
>>> Then, the list is arbitrarily truncated after that limit.
>>
>> You have to be a bit careful not to evaluate the local
>> containing such a long string (i.e. avoid using the "=" when
>> defining a local), but otherwise there should not be a
>> problem with -gettoken- or the extended macro functions (I
>> always type -help macro- and follow the link to the helpfile
>> for the extended macro functions), even if the local surpasses
>> the 244 tokens limit. This is illustrated in the example
>> below:
>>
>> *------------ begin example -------------------
>> forvalues i = 1/60 {
>>        local lstring "`lstring' very"
>> }
>> local lstring "`lstring' long string"
>>
>> // the string has more than 244 characters:
>> di `: length local lstring'
>>
>> // -gettoken- works:
>> gettoken first rest : lstring
>> di `:length local first'
>> di `:length local rest'
>> *------------- end example --------------------
>> (For more on how to use examples I sent to the Statalist, see
>> http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )
>>
>> Hope this helps,
>> Maarten
>>
>> -----------------------------------------
>> Maarten L. Buis
>> Institut fuer Soziologie
>> Universitaet Tuebingen
>> Wilhelmstrasse 36
>> 72074 Tuebingen
>> Germany
>>
>> http://home.fsw.vu.nl/m.buis/
>> -----------------------------------------
>>
> *
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>

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