This works, but it is rather a roundabout solution,
with some disadvantages.
local vl "`vl' `v'"
is better in a loop than
local vl = "`vl' `v'"
as the latter can hit limits on length of expressions
and give rise to bugs.
When it is necessary to unpack a varlist into
discrete items, the most direct approach is not
a loop but
unab varlist : _all
or
unab varlist : *
However, note that these macros will include the
names of any temporary variables in existence. If
it were needed, I guess that the most direct way
to gather names of temporary variables would be
unab temp : __*
where the underscore is doubled. This is based
on the assumption that no permanent variable
has a name starting with an underscore.
I follow Phil Schumm in preferring something like
unab varlist : _all
unab exclude : <whatever>
local varlist : list varlist - exclude
-ds <whatever>, not- gets you to the same place, more
or less, but with more interpretative overload.
Nick
[email protected]
Doug Owens
Another solution I sometimes use is of the form:
sysuse auto, clear
foreach var of varlist _all {
local vl = "`vl' `var'"
}
local exclude "trunk weight disp length mpg make"
local vl: list vl - exclude
di "`vl'"
local
> using the foreach command I would like to exclude certain variables,
> e.g:
> "foreach var of varlist _all [/excluding a, b, c/]".
>
> Is that possible and if so how?
*
* 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/
