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AW: AW: st: -if- and r() in -histogram-


From   "Martin Weiss" <[email protected]>
To   <[email protected]>
Subject   AW: AW: st: -if- and r() in -histogram-
Date   Thu, 4 Feb 2010 15:15:00 +0100

<> 

In other instances, you do get away with plain references to the r-return
values:


*************
sysuse auto, clear
su mpg, d
cou if mpg>r(p75)
su mpg, d
cou if mpg<r(p75)
su mpg, d
cou if mpg>`r(p75)'
su mpg, d
cou if mpg<`r(p75)'
*************



HTH
Martin


-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von Antoine
Terracol
Gesendet: Donnerstag, 4. Februar 2010 15:08
An: [email protected]
Betreff: Re: AW: st: -if- and r() in -histogram-

So I guess that to be on the safe side one should use `r()' in every 
-if- statement. That should be made clearer in [U]18, section 18.8. 
There might be technical reasons, but why not mark the relevant 
subsample right after parsing the command, rather than when the content 
of the -if- statement could have been modified by subroutines?

Antoine



Nick Cox wrote:
> `r(95)' is evaluated before -histogram- even opens: -histogram- sees only
the numeric result. 
> 
> That's not true of r(95). In the first instance the text "r(95)" is used
and only later it is evaluated. 
> 
> That is, you want -histogram- to work with a pre-existing r(95), but
inside -histogram- other r-class results are produced and that undermines
your aim. 
> 
> Nick 
> [email protected] 
> 
> Antoine Terracol
> 
> True, but I find it strange that references to r() work with -kdensity- 
> (or commands like -summarize-), but hot with -histogram- (nor with 
> -graph box-) where `r()' seems to be required.
> 
> Martin Weiss wrote:
>> <> 
>>
>> You do get the correct graph with:
>>
>> *************
>> clear
>> cap graph drop _all
>> set obs 1000
>> g x=exp(rnormal())
>> su x, de
>> hist x if x<`r(p95)', name(ha)
>> *************
>>
>>
>>
>> HTH
>> Martin
>>
>> -----Ursprüngliche Nachricht-----
>> Von: [email protected]
>> [mailto:[email protected]] Im Auftrag von Antoine
>> Terracol
>> Gesendet: Donnerstag, 4. Februar 2010 13:24
>> An: [email protected]
>> Betreff: Re: st: -if- and r() in -histogram-
>>
>> <>
>>
>> of course, all the "hist" below should be "kdensity", and the correct 
>> piece of code is
>>
>> /**********************/
>> clear
>> cap graph drop _all
>> set obs 1000
>> g x=exp(rnormal())
>> su x, de
>> local p95=r(p95)
>> di r(p95)
>> kdensity x if x<r(p95), name(ka)
>> kdensity x if x<`p95', name(kb)
>> kdensity x, name(kc)
>> /************************/
>>
>> Antoine Terracol wrote:
>>> Now, I have not tried all types of graphs, but -kdensity- seems to 
>>> behave as expected:
>>>
>>> /**********************/
>>> clear
>>> cap graph drop _all
>>> set obs 1000
>>> g x=exp(rnormal())
>>> su x, de
>>> local p95=r(p95)
>>> di r(p95)
>>> hist x if x<r(p95), name(ka)
>>> hist x if x<`p95', name(kb)
>>> hist x, name(kc)
>>> /************************/
> 
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