Dear list-members,
Thank you very much for all your suggestions. I must say,
joining this list has been a good learning experience.
For the sake of it, I tried all the solutions suggested and
most worked.
Nick's solution: Using ${X`p'} worked well. (As regards
the awkward numbering - in my present scenario, it's easier
for me to use it as such; moreover, I was interested in
knowing how to use local macros within global macros, and
the current problem provided a good opportunity, so I kept
the numbering as it is.)
Kris' solution: Defining my globals as locals instead (I
would call them global macros and local macros but I am not
sure; perhaps, Nick can clarify) and then writing `X`p''
worked, too.
Alex's solution was right in principle but involved a small
typo. Instead of:
local globalname "X`np1'"
reg y`n' $X`globalname'
it should be
local globalname "`X`np1''"
reg y`n' `globalname'
And finally, Prabhu was right, too - Kris' solution doesn't
work if I retain the global macros.
Thank you very much, everyone.
Regards,
Nishant
--- Nick Cox <[email protected]> wrote:
> The previous posting explained that the
> terminology "variable" is not appropriate
> here.
>
> Your main question was answered earlier this month
> in this posting:
>
> =============================================
> st: RE: Variable names incompatable with aflogit?
> Date: Fri, 11 Aug 2006 20:03:23 +0100
>
> The problem is with references to
>
> $`1'
>
> where Stata is expected by the programmer
> to take the local macro name first and then
> evaluate the global name that results. If that
> is what you want, you are expected to spell that
> out explicitly.
>
> Presumably this worked at one point, but
> (again I surmise) StataCorp perhaps tightened
> up on what was seen as a bug or a misfeature.
>
> A quick experiment indicates that changes
> to the code so that these lines read as below
> produces output.
>
> 212 replace `1' = ${`1'} - `1'
> 241 gen `zmx' = ${`1'} - `1'
> 272 replace `1' = ${`1'} if `1' != .
> 281 replace `1' = ${`1'} if `1' != . /* reset
> exposure to reference level */
>
> That is, assignments referring to
>
> $`1'
>
> should be to
>
> ${`1'}
>
> instead.
>
=============================================================
>
> In your case, your code would be better off as
>
> forvalues n = 1/10 {
> local p = `n' + 1
> reg y`n' ${X`p'}
> }
>
> which forces Stata to delay evaluation of the global
> macro name until it has evaluated the local macro
> name.
>
> But look at your code. You are looping over n
> and also over p, by an explicit increment.
>
> That's because you have your global macro
> numbering out of sync with your y numbering.
> I would sort that out upstream, so that
> you can just go
>
> forvalues n = 1/10 {
> reg y`n' ${X`n'}
> }
>
> The reason is that if your numbering is awkward for one
> bit
> of code, it is going to be awkward for other
> bits too. All this code is going to be harder to
> write, harder to read, and more prone bugs
>
> If there is some compelling argument not
> to do what looks dopey on the evidence available, then
> note another way to do it:
>
> forval n = 1/10 {
> reg y`n' ${X`=`n' + 1'}
>
> but I recommend tidying up over trickery every
> time.
>
> Nick
> [email protected]
>
> Nishant Dass
>
> > I have a small (or so it seems) problem with a loop
> (shown
> > below).
> >
> > I start by generating a few global macros:
> > global X2 "age2 weight2 height2"
> > global X3 "age3 weight3 height3"
> > ...
> > global X11 "age11 weight11 height11"
> >
> > Then I try to run the following set of regressions
> using a
> > loop:
> > forvalues n = 1/10 {
> > local p = `n' + 1
> > reg y`n' $X`p'
> > }
> >
> > However, this isn't executed due to an error that says
> "2
> > invalid name" (i.e., it's referring to some problem in
> the
> > way I have used `p' in $X`p'.)
> >
> > Could anyone please tell me what would be the correct
> way
> > to do this?
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
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