The -levelsof- solution is one I would endorse.
For people interested in tricks in this territory,
FAQ . . . . . . . . . . Making foreach go through all values of a variable
8/05 Is there a way to tell Stata to try all values of a
particular variable in a foreach statement without
specifying them?
http://www.stata.com/support/faqs/data/foreach.html
talks about the -levelsof-/-foreach- manoeuvre and alternatives.
Nick
[email protected]
Philipp Rehm
> A potential work-around on a command that's not by-able is to use
> -levelsof- in combination with a loop.
>
> Example: Assume you want price deciles by car type (foreign). The
> following may get you there:
>
> sysuse auto, clear
>
> gen deciles_price=.
> levelsof foreign, local(l)
> foreach C in `l' {
> xtile deciles_price_`C'=price if foreign==`C', n(10)
> replace deciles_price=deciles_price_`C' if foreign==`C'
> drop deciles_price_`C'
> }
>
> You can make this loop arbitrarily complicated to incorporate more
> variables (although it's not particularly pretty to read):
> Just add more
> -levelsof- and -foreach--loops.
>
> There may well be much better ways to do this, though.
>
Thomas Erdmann wrote:
> > A further note on Jeph's suggestion:
> >
> > It looks very convenient, but I need to adjust for the fact
> that I do not
> > need the mean of the same item but of a different attribute:
> >
> > foreach X of varlist c1* {
> > xtile deciles_`X'=`X', n(10)
> > bysort deciles_`X': egen Rr`X'=mean(c1ds_ri)
> > }
> >
> > But a problem still remains:
> > the deciles are calculated over all observations - but what
> I need is
> > calculating the mean of deciles by yrm (my time variable
> representing
> > YearMonth) and afterwards the mean of all deciles groups
> (1-10) over all
> > yrm's. I was not able to integrate this into this short
> solution as -by- is
> > not allowed for -xtile- .
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