As a kind of meta-comment I recommend against the use of "unique" in
this context.
"Unique" means occurring once only. It's a good word, and best left to
mean that, as your school teachers may have urged. For example,
"StataCorp is a unique company". Very true (if also trite).
Naturally, some might want to start the age-old discussion of whether
usage sanctifies abuse of etymology. But even descriptively-inclined
dictionaries don't seem to sanction the sense of this word "unique" as
meaning "distinct", which I suggest is a much better word than
"unique" for this purpose.
My guess is that the popularity of "unique" in this meaning stems
partly from Unix utilities such as -uniq-, which removes copies from a
list and leaves one and one copy of each distinct item as a result.
Thus
a a a b b c
would be reduced to
a b c
by such utilities.
Here uniqueness defines each item in the result, not each item in the
argument. My guess is that many software developers encountered such
utilities such as -uniq- in their youth and that had a greater
influence on them than their English dictionaries (if they had one) or
their English teachers (if they paid them much attention).
I have a long-term plan to persuade StataCorp of this too. See also
SJ-8-4 dm0042 . . . . . . . . . . . . Speaking Stata: Distinct observations
(help distinct if installed) . . . . . . N. J. Cox and G. M. Longton
Q4/08 SJ 8(4):557--568
shows how to answer questions about distinct observations
from first principles; provides a convenience command
I can't speak authoritatively on languages other than English -- "not
even", some might think -- so not mentioning them means only that.
Nick
On Mon, Jan 21, 2013 at 2:30 PM, Maarten Buis <maartenlbuis@gmail.com> wrote:
// collect the values
levelsof var1, locals(loc1)
levelsof var2, locals(loc2)
// stack the macros
// NOTICE: no "=" sign
local loc "`loc1' `loc2'"
// get rid of the duplicates
local loc : list uniq loc
For more see: -help extended_fcn- and especially -help macrolists-
Hope this helps,
Maarten
On Mon, Jan 21, 2013 at 3:02 PM, Roberto Liebscher
<roberto.liebscher@ku.de> wrote:
I have two variables both containing string values. I would like to get all
unique values (not the number of unique values) from these two variables
jointly.
For example if I enter
levelsof var1, locals(loc1)
levelsof var2, locals(loc2)
I obtain all unique values of var1 and all unique values of var2. But at the
end I would like to have one local containing only unique values in loc1 AND
loc2.
Is there anyone who can help me with this?
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