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RE: st: Puzzled by behavior of -recode varlist (.a/.z=.)-


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Puzzled by behavior of -recode varlist (.a/.z=.)-
Date   Fri, 23 Apr 2004 19:29:07 +0100

But .a etc. are being compared as string equivalents, 
".a" etc., presumably because of this behaviour of -inrange()- 
with numeric missings. And it makes sense to ask 
whether some string lies between ".a" and ".z"
in ASCII order. 

Nick 
n.j.cox@durham.ac.uk 

Richard Williams
> 
> Definitely sounds like odd behavior to me.  Looking at 
> -recode.ado-, I 
> notice there are these lines:
> 
>          else if length(`"`v'"')==2  &  inrange(`"`v'"',".a",".z") {
>                  return local s1 `v'
> 
> Now, I haven't waded through the whole ado file, but I wonder 
> if that line 
> is doing what it is supposed to do.  According to the online 
> docs for inrange,
> 
>      "inrange(z,a,b) returns 1 if it is known that a <= z <= 
> b; otherwise, 
> this function returns 0.  If z = missing (.) this function 
> returns 0.  For 
> numeric arguments, if a = missing and/or b = missing these values are 
> interpreted as a = -infinity and/or b = +infinity, respectively."
> 
> Now, I just tried the command
> 
> . gen z = inrange(var1, .a, .z)
> 
> where var1 was a mixture of missing and nonmissing values, 
> and z = 0 for 
> every case.  This is consistent with the docs saying "If z = 
> missing (.) 
> this function returns 0" but it is not consistent with what the users 
> intent would probably be in this case.
> 
> Anyway, it is hard for me to believe that this is not a bug, 
> and my wild 
> guess is that it might have something to do with the use of 
> the inrange 
> command as shown above.  But, it could be something else.

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