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

[Philipp Rehm <philipp.rehm@gmx.de>]

.
Thanks, Paul.

You wrote:
"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."

Alas, that's exactly my problem. I need to grab *_*, because I don't 
know which subscripts are present or absent.

(Since this may sound a little strange, let me explain why this is so. I 
have a data-set with thousands of variables over a maximum of 40 years 
or so, in wide format. The problem is that not all variables are present 
for all years, which is why I prefer to grab everything and get the 
stubs from there).

Thanks again,
Philipp


E. Paul Wileyto wrote:

> 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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