Michael Blasnik pointed to the main
issue, the problem raised by assignment rather than
copying.
A secondary detail is that your new names are
not informative. Provided that your variable
names are not too long, you can copy them over.
local difreg
foreach v of varlist $lhs $rhs2 {
gen d`v'=(`v'-`v'[_n-1])/sqrt(2)
local difreg "`difreg' d`v'"
}
regress `difreg'
The initialisation of the macro to an empty string
is essential only if it already exists.
Nick
[email protected]
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Ken Clark
> Sent: 23 January 2004 12:15
> To: [email protected]
> Subject: st: Creating list of transformed variables
>
>
> Dear List
>
> I'm trying (in Stata 7) to automate the estimation of a regression
> model on transformed data. I have a dependent variable, the name
> of which is stored in $lhs, and some independent variables which
> are in $rhs2. I'd like to transform (quasi-difference) each variable
> and then run a regression on the transformed data. The code
> below represents my attempt at this.
>
> global difreg=""
> local i=1
> foreach var of varlist $lhs $rhs2 {
> gen d`i'=(`var'-`var'[_n-1])/sqrt(2)
> global difreg="$difreg"+" "+"d`i'"
> local i=`i'+1
> }
> regress $difreg
>
> This seems to work fine so long as $rhs2 is not too long. If there
> are a lot of variables in $rhs2 then Stata stops adding to $difreg
> and the program either stops executing because $difreg is not a
> valid list of variables or (worse) runs with an incomplete list of
> variables.
>
> I'm sure a more elegant solution exists but am not sure where to
> look.
>
> Ken
>
>
>
>
> Ken Clark
> School of Economic Studies
> University of Manchester
> Manchester
> M13 9PL
> Tel:0161-275-3679
> Fax:0161-275-4812
> email: [email protected]
> http://www.ses.man.ac.uk/clark
> *
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*
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