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Re: st: loop until "0 real changes made"


From   Sergiy Radyakin <serjradyakin@gmail.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: loop until "0 real changes made"
Date   Mon, 29 Jul 2013 16:16:36 -0400

-Clonevar- uses the information that the width of the result is known,
so compared to unassisted -generate- it saves, basically a -compress-
cycle. However the pure -generate- with type specified is still about
10% faster then -clonevar- in your example (single CPU Stata):

. forval i=1/100 {
  2.
.    timer on 1
  3.    clonevar s2 = s
  4.    timer off 1
  5.
.    timer on 2
  6.    gen `:type s' s4 = s
  7.    timer off 2
  8.
.    drop s2 s4
  9. }
r; t=44.60 15:58:21

.
. timer list
   1:     23.10 /      100 =       0.2310
   2:     21.47 /      100 =       0.2147

Best, Sergiy



On Mon, Jul 29, 2013 at 3:42 PM, Robert Picard <picard@netbox.com> wrote:
> Perhaps an example will explain why...
>
> * --------------- begin example ---------------------------
> clear
> set obs 1000000
>
> set rms on
>
> gen s = string(uniform(),"%21x")
> clonevar s2 = s
> gen s3 = s
>
> gen `:type s' s4 = s
>
> * --------------- end example -----------------------------
>
>
>
> On Mon, Jul 29, 2013 at 3:34 PM, Sergiy Radyakin <serjradyakin@gmail.com> wrote:
>> On Mon, Jul 29, 2013 at 3:19 PM, Robert Picard <picard@netbox.com> wrote:
>>> Here's a more complete example of how to continue making substitutions
>>> until there are no more changes. I'm with Nick on using -clonevar-
>>> when making an exact copy of a variable, it is faster than -generate-
>>
>> Pardon my ignorance, but how is -clonevar- (implemented as an ado
>> program) possibly faster than -generate- (built-in), if it is using
>> -generate- inside and on top of that does some other things?? (like
>> copying labels, formats, etc, which are not necessary for this
>> exercise).
>>
>> From clonevar.ado ( 1.0.1  13oct2004):
>> gen `type' `newvar' = `varname' `if' `in'
>>
>> Sergiy
>>
>> .
>>> Also, avoid -regexr()- in Stata 13, it's slow as molasses.
>>>
>>> * --------------- begin example ---------------------------
>>> clear
>>> set obs 100000
>>>
>>> gen AD1 = string(uniform(),"%21x")
>>> gen AD2 = string(uniform(),"%21x")
>>> list in 1/5
>>>
>>> foreach v of var AD* {
>>>         local more 1
>>>         while `more' {
>>>                 clonevar stemp = `v'
>>>                 replace `v' = subinstr(`v',"0X-","X-",.)
>>>                 count if `v' != stemp
>>>                 local more = r(N)
>>>                 drop stemp
>>>         }
>>> }
>>> list in 1/5
>>> * --------------- end example -----------------------------
>>>
>>>
>>> On Mon, Jul 29, 2013 at 12:34 PM, Sergiy Radyakin
>>> <serjradyakin@gmail.com> wrote:
>>>> Nick's solution with two variables is the most generic approach that
>>>> is useful in situations where it is difficult to predict if any
>>>> changes are going to happen as a result of your code. It certainly is
>>>> going to work here as well (I would only use a tempvar instead of AD2
>>>> and generate instead of clonevar).
>>>>
>>>> However, why would you do this recoding to non-Turkish characters?
>>>> Stata works with Turkish characters like with any other for which a
>>>> corresponding ANSI page is available and proper font is installed:
>>>>
>>>> http://radyakin.org/statalist/2013072901/turkish.png
>>>> http://radyakin.org/statalist/2013072901/turkish.do
>>>>
>>>> The ANSI page for Turkish is 1254. And I would try e.g.:
>>>> replace `v'=regexr(`v', "`=char(196)'+`=char(158)'","`=char(208)'")
>>>> instead of
>>>> replace `v'=regexr(`v', "`=char(196)'+`=char(158)'","G")
>>>>
>>>>
>>>> Best, Sergiy Radyakin
>>>>
>>>> On Mon, Jul 29, 2013 at 10:06 AM, Nick Cox <njcoxstata@gmail.com> wrote:
>>>>> Plus the "+" if needed.
>>>>> Nick
>>>>> njcoxstata@gmail.com
>>>>>
>>>>>
>>>>> On 29 July 2013 15:05, Nick Cox <njcoxstata@gmail.com> wrote:
>>>>>> One answer is not to use regular expressions here at all. Use
>>>>>> -subinstr()- with statements like
>>>>>>
>>>>>> replace `v' = subinstr(`v', "`=char(195)'`=char(135)'","C", .)
>>>>>>
>>>>>> Another answer is to set up a count of changes and stop when you hit zero.
>>>>>>
>>>>>> clonevar AD2 = AD
>>>>>>
>>>>>> foreach v of var AD {
>>>>>>            replace AD2 = AD
>>>>>>            <work with AD>
>>>>>>            count if AD2 != AD
>>>>>>            if r(N) == 0 continue, break
>>>>>> }
>>>>>>
>>>>>> Nick
>>>>>> njcoxstata@gmail.com
>>>>>>
>>>>>> On 29 July 2013 14:48, Haluk Vahaboglu <vahabo@hotmail.com> wrote:
>>>>>>
>>>>>>> I am using Stata 12.1 for Linux-64 bit and dealing with Turkish characters in string variables. I convert these Turkish characters (ı, ş, ü etc) to readable equivalents (i, s, u etc). Doing this with the code below:
>>>>>>>
>>>>>>> foreach v of var AD {
>>>>>>>            replace `v'=regexr(`v', "`=char(195)'+`=char(135)'","C")
>>>>>>>            replace `v'=regexr(`v', "`=char(196)'+`=char(176)'","I")
>>>>>>>            replace `v'=regexr(`v', "`=char(195)'+`=char(167)'","c")
>>>>>>>            replace `v'=regexr(`v', "`=char(195)'+`=char(182)'","o")
>>>>>>>            replace `v'=regexr(`v', "`=char(196)'+`=char(177)'","i")
>>>>>>>            replace `v'=regexr(`v', "`=char(196)'+`=char(158)'","G")
>>>>>>>            replace `v'=regexr(`v', "`=char(196)'+`=char(159)'","g")
>>>>>>>            replace `v'=regexr(`v', "`=char(195)'+`=char(156)'","U")
>>>>>>>           replace `v'=regexr(`v', "`=char(195)'+`=char(188)'","u")
>>>>>>>           replace `v'=regexr(`v', "`=char(197)'+`=char(158)'","S")
>>>>>>>           replace `v'=regexr(`v', "`=char(195)'+`=char(150)'","O")
>>>>>>>           replace `v'=regexr(`v', "`=char(197)'+`=char(159)'","s")
>>>>>>> }
>>>>>>>
>>>>>>> However, this code cannot accomplish the conversion at the first time. Therefore, I have to do it 5 to 10 times to get a (0 real changes made) message.
>>>>>>> My question is: can I make this loop run automatically until I get the (0 real changes made) message which indicates that all characters are converted.
>>>>>
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