Scalars and variable names share the same name space. That is in the
manual [P]
and discussed at length within
SJ-6-2 dm0019 . Stata tip 31: Scalar or variable? Problem of ambiguous
names
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . G. I.
Kolev
Q2/06 SJ 6(2):279--280 (no
commands)
tips for avoiding abbreviation conflicts with variables
when naming scalars
What you want is
tempname mu
scalar `mu' = <whatever>
Similarly, it is good practice to use tempnames for all scalars within
programs, unless you have
a very good reason to the contrary.
If you go
tempname mu
scalar mu = <whatever>
then that is legal, but makes no use of the tempname.
If you use tempnames for all your scalars, there will be no clash
between scalar names and
existing variable names, and no need to fiddle with whether variable
abbreviation is on or off. In any case, note that if you have a scalar
mu
and a variable name mu, then there is a clash regardless of whether
variable
names can be abbreviated. In fact, I don't think you should mess with
variable
abbreviation in most programs.
Nick
[email protected]
Dirk Enzmann
Does somebody have an idea why I receive the error message "mu ambiguous
abbreviation" if the data contain variable starting with mu...? Below
the result of trying to run my program "fitnb" with - set trace on -
and - set tracedepth 1 -.
I thought that using "tempvar mu" followed by "scalar mu = something"
would result in mu being a temporary scalar (no macro!) existing only
within the call of the program fitnb.
BTW, is there a possibility to check quietly the setting of varabbrev?
So that I could use "set varabbrev off" at the beginning of the program
and "set varabbrev on" at the end only if it has been "on" before (so
that a call to the program will never change the setting "varabbrev"
outside the program)? Because to use "set varabbrev off" is an effective
workaround.
Thanks in advance,
Dirk
=====================================================================
fitnb rbinz99
----------------------------------------------------- begin fitnb ---
- version 9
- syntax [varlist] [, maxval(integer 0)]
- tokenize `varlist'
= tokenize rbinz99
- args x
- tempvar x_max size mu N prob i nbdat maxfit pmisfit
- if `maxval'==0 {
= if 0==0 {
- local selection "if `x'<."
= local selection "if rbinz99<."
- }
- else {
local selection "if `x'<. & `x'<=`maxval'"
}
- sum `x' `selection'
= sum rbinz99 if rbinz99<.
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
rbinz99 | 9081 .2542672 2.124223 0 150
- scalar x_max = r(max)
- quietly nbreg(`x') `selection'
= quietly nbreg(rbinz99) if rbinz99<.
- scalar size = 1/exp(_b[/lnalpha])
- scalar mu = exp(_b[_cons])
- scalar N = e(N)
- scalar prob = size/(size+mu)
mu ambiguous abbreviation
------------------------------------------------------- end fitnb ---
r(111);
=====================================================================
--
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