Re: st: How to write byable ado file that adds variables to data

[Phil Clayton <philclayton@internode.on.net>]

One option is to check whether or not the variable already exists, using that to determine whether to -gen- or -replace- the variable. For example:

capture confirm new variable newvar
if !_rc {
	gen newvar=... if `touse'
}
else replace newvar=... if `touse'

Phil

On 23/11/2011, at 10:49 PM, Richard Herron wrote:

> It appears that my first program doesn't work without -by-, either (I
> must have had the original program cashed). Here is the program that
> works without -by-. Thanks!
> 
> *! price_fun v0.1 Richard Herron 11/21/2011
> program price_fun
>    version 11.2
>    args price eps1 eps2 eps3 eps4 eps5 beta bkvlps rf r g
>    tempvar ri num den
>    generate `ri' = `rf' + `beta'*`r'
>    generate price_hat_`rf'_`r'_`g' = `bkvlps' ///
>        + `eps1'/(1 + `ri'/100) ///
>        + `eps2'/(1 + `ri'/100)^2 ///
>        + `eps3'/(1 + `ri'/100)^3 ///
>        + `eps4'/(1 + `ri'/100)^4 ///
>        + `eps5'/(1 + `ri'/100)^5 ///
>        + (1 + `g'/100)*`eps5'/(`ri'/100 - `g'/100)/(1 + `ri'/100)^5
>     generate `num' = abs(price_hat_`rf'_`r'_`g' - `price')
>     egen `den' = rowmin(price_hat_`rf'_`r'_`g' `price')
>     generate w_`rf'_`r'_`g' = `num'/`den'
> end
> 
> On Wed, Nov 23, 2011 at 07:03, Richard Herron
> <richard.c.herron@gmail.com> wrote:
>> I am writing my first byable program. The program works without -by-,
>> but with -by- it fails on the second subset with the error "_variable_
>> already defined." This is logical because I am adding two variables to
>> my data, but I am not sure of the work-around. Is it not possible to
>> add variables in a byable program? Thanks!
>> 
>> Here is the program.
>> 
>> *! price_fun v0.1 Richard Herron 11/21/2011
>> program price_fun, byable(recall)
>>    version 11.2
>>    syntax varlist(min=11 max=11 numeric) [if] [in]
>>    marksample touse
>>    tokenize `varlist'
>>    local price `1'
>>    local eps1 `2'
>>    local eps2 `3'
>>    local eps3 `4'
>>    local eps4 `5'
>>    local eps5 `6'
>>    local beta `7'
>>    local bkvlps `8'
>>    local rf `9'
>>    local r `10'
>>    local g `11'
>>    tempvar ri num den
>>    generate `ri' = `rf' + `beta'*`r' if `touse'
>>    generate price_hat_`rf'_`r'_`g' = `bkvlps' ///
>>        + `eps1'/(1 + `ri'/100) ///
>>        + `eps2'/(1 + `ri'/100)^2 ///
>>        + `eps3'/(1 + `ri'/100)^3 ///
>>        + `eps4'/(1 + `ri'/100)^4 ///
>>        + `eps5'/(1 + `ri'/100)^5 ///
>>        + (1 + `g'/100)*`eps5'/(`ri'/100 - `g'/100)/(1 + `ri'/100)^5 ///
>>        if `touse'
>>     generate `num' = abs(price_hat_`rf'_`r'_`g' - `price') if `touse'
>>     egen `den' = rowmin(price_hat_`rf'_`r'_`g' `price') if `touse'
>>     generate w_`rf'_`r'_`g' = `num'/`den' if `touse'
>> end
>> *
>> *   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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