Re: st: Selecting stubnames for -reshape- / macrolists

["E. Paul Wileyto" <epw@mail.med.upenn.edu>]

I have the following implemented as an ADO.  It is what I use to grab 
all the name stubs for reshaping.  You will want to make sure that if 
your subscripts all look like _1, _2, _3... that you only use one of 
them.  Grabbing *_* will give the same stubname many times.

Paul

program define namelist

***********************************************************************
***********************************************************************
*  This short program helps you define a list (global macro vlist)
*  of variable name roots to aid in scripting and especially reshaping.
*
*  Feel free to use wildcards in varlist.  Be sure that you are only
*  generating the same root once.
*
*  The oldsub option describes the common subscript in the the list.
*  The newsub option describes the truncated subscript to be used in
*  reshaping.
* 
*  For example:  Variables rx30a_s1..rx30a_s20 all have the common root
*  rx30a_s, with a numerical subscript for the repetition.  To extract a
*  list of roots for all survey entries, use:
*
*  -namelist rx*_s1, oldsub(_s1) newsub(_s)
*
***********************************************************************
***********************************************************************

syntax varlist, [oldsub(string) newsub(string)]
global vlist "`varlist'"
if "`oldsub'" > "" & "`newsub'" > "" {
global vlist : subinstr local varlist "`oldsub'" "`newsub'" , all
}
noisily ma list vlist
end


pr9@duke.edu wrote:

> .
> My question is whether there is a clever way to identify the stubnames
> for a -reshape-. Consider this example:
>
> sysuse auto, clear
> foreach j in 1 2 3 4 5 {
>     gen x_`j'=rep78+`j'
>     gen y_`j'=rep78-`j'
> }
> drop y_3
> gen id=_n
> keep id x_* y_*
>
> /*
> This data-set contains the following variables which I want to -reshape-:
> x_1  x_2  x_3  x_4  x_5
> y_1  y_2       y_4  y_5
> I want to -reshape- by stubnames x_ and y_.
> In my "real" data-set, I know that all variables I want to end up with
> as stubnames contain an underscore (_). They all also do contain numbers
> after the underscore, but there is no regular pattern there.
>
> Now, I am generating a -macrolist- with unique stubnames, but this seems
> like a detour to me, especially the loop:
> */
>
> ds *_*
> foreach v in `r(varlist)' {
>         local f `=regexr("`v'","[0-9]+","")'
>         local n `n' `f'
>         local n: list uniq n
> }
> di "*** `n' ****"
> reshape long `n', i(id) j(foo)
>
> Two questions:
> 1) Is there a better way to identify stubnames for a -reshape-?
> 2) Is there a more straightforward way to arrive at a unique macrolist
> than the one I chose? In particular, something like the -regexr()-
> function, but with the ability to remove all instances (not just the
> first) of the regular expression. Something like -subinstr()-, but for
> regular expressions.
>
> Thank you!
> Philipp
>
>
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--
E. Paul Wileyto, Ph.D.
Assistant Professor of Biostatistics
Tobacco Use Research Center
School of Medicine, U. of Pennsylvania
3535 Market Street, Suite 4100
Philadelphia, PA  19104-3309

215-746-7147
Fax: 215-746-7140
epw@mail.med.upenn.edu
http://mail.med.upenn.edu/~epw/ 
*
*   For searches and help try:
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*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/