Re: st: Question using macro in loop

[Tak-wai Chau <tchau@troi.cc.rochester.edu>]

Hi, Friedrich and other statalisters,

Thanks for Friedrich's reply.

Sorry that I made a mistake in my code. I mean "gen s=1" instead of 
"s=1". The missing values appear at different variables for different 
observations, so s would take different values for different 
observations. Also, what I want is that, for example, if all Vi are not 
missing except V5, then the resulting Wi would be that W1-W4 would be 
the same as V1-V4, while W5-W9 would carry values from V6-V10.

Thanks a lot!

Tak Wai

Friedrich Huebler wrote:

> Tak Wai,
>
> The loop below copies all non-missing observations from variables v1
> to v10 to variables w1 to w10. The macro s counts the number of
> non-missing observations in variables v1 to v10.
>
> local s = 0
> forvalues i = 1/10 {
>   replace w`i' = v`i' if v`i'<.
>   count if v`i'<.
>   local s = `s' + r(N)
>   di `s'
> }
>
> The statement "s=1" is not valid Stata, you probably mean "generate
> s=1". The command "local s1=s" assigns the first observation in
> variable s to the local s1. The command "replace s=s+1 if v`i'<."
> adds 1 to all observations in variable s if the first observation in
> variable v`i' is missing.
>
> The command "replace w`s1'=v`i' if v`i'<." indicates that you may be
> thinking in terms of a loop over observations, not variables. Such a
> loop is neither efficient nor necessary but if you want it you need
> different code from the one above.
>
> Friedrich
>
> --- Tak-wai Chau <tchau@troi.cc.rochester.edu> wrote:
> > Hi,
> >
> > I would like to ask something about using macro in loops. I have
> > tried to find it in the archive and FAQ for some time but I don't
> > get it.
> >
> > Sorry if I have overlooked some obvious things.
> >
> > I would like to update certain variables according to the value
> > taking by a particular variable, and this value differs by
> > observations. Then what I should do?
> >
> > For example, if I want to transfer value of non-missing variables
> > from V1-V10 to W1-W10. But I don't want to variables carrying 
> > missing value between. I use s to count the number of non-missing
> > values I have covered at that point.
> >
> > The following is what I think of but doesn't work.
> >
> > s=1
> > forvalues i=1/10 {
> > 	local s1=s
> > 	replace w`s1'=v`i' if v`i'<.
> > 	replace s=s+1 if v`i'<.
> > }
> >
> > I know the problem is at the local statement.
> >
> > What should I do?
> >
> > Thank you very much!
> >
> > Tak Wai Chau
>
>
>
>
>
>
>
>  
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