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Re: st: renaming variables from first observation


From   Matthew White <mwhite@poverty-action.org>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: renaming variables from first observation
Date   Thu, 25 Aug 2011 09:57:43 +0000

It'd create longer variable names, but maybe -strtoname()- is another option?

Best,
Matt

On Thu, Aug 25, 2011 at 9:27 AM, Nick Cox <njcoxstata@gmail.com> wrote:
> In fact, much of the last part of this to with -renvars- is a red
> herring. I was wondering exactly why my code with -renvars- worked; I
> just figured out that it was an accident in the original example in
> which buggy code gave the right answer for the wrong reason.
>
> Better code is
>
> renvars , map(word(@[1], 1))
>
> This should be more transparent. The idiosyncratic detail is that @ is
> a placeholder for each variable name in turn. The recipe then is to
> use the first word of the value in the first observation. So for
> -var1- the new name would be the value of
>
> word(var1[1], 1)
>
> Nick
>
> On Thu, Aug 25, 2011 at 10:13 AM, Nick Cox <njcoxstata@gmail.com> wrote:
>> Let's assume that your first values are all legal names. You could
>> indeed do this
>>
>> forval j  = 1/14 {
>>      local names `names' `=var`j'[1]'
>> }
>> renvars var1-var14 \ `names'
>>
>> But that's actually dozens of lines more code (look _inside_ -renvars-)  than
>>
>> forval j = 1/14 {
>>     rename var`j' `=var`j'[1]'
>> }
>>
>> and the second is in any case shorter and more direct, even without
>> looking inside -renvars-.
>>
>> You asked what a solution was with -renvars- and I agree that it looks
>> complicated. The -map()- option was mine and intended as an outlet for
>> the desperate user-programmer whose problem was not met by any of the
>> other options. But usually you need to be moderately fluent in Stata
>> to make effective use of it. The program was written for the authors'
>> use and any utility beyond that is a pleasant side-effect!
>>
>> `= exp'
>>
>> evaluates an expression on the fly and is documented tersely at -help
>> macro-. But the main idea is simple. Consider as part of a command
>> line
>>
>> `= 2 + 2'
>>
>> Stata sees ` ' and so expects something like a macro reference to be
>> substituted. But instead of a macro name there is
>>
>> = 2 + 2
>>
>> Stata does the calculation on the fly. In this case the result is 4
>> and that is what the command would see.
>>
>> -renvars- is over a decade old now. After that length of time
>> StataCorp caught up and the official -rename- is now much versatile in
>> Stata 12, although I doubt it has a way to solve your problem without
>> a loop. I would be happy to be shown wrong on that.
>>
>> Nick
>>
>>
>> On Thu, Aug 25, 2011 at 9:50 AM, Abhimanyu Arora
>> <abhimanyu.arora1987@gmail.com> wrote:
>>> Yes Nick, precisely, my values in the first observation were not
>>> legal. What I meant by storing values in a macro was something like a
>>> horizontal -levelsof- command. Once I obtain the values in a single
>>> macro I thought of simply using your and Jeroen Weesie's -renvars-.
>>>
>>> But the map option seems not that easy to understand, perhaps because
>>> I find `quotes' confusing sometimes. One needs to have a string
>>> expression in the parentheses while using the map option but I see
>>> that the expression in your example is in `quotes', normally used for
>>> macros. Would be really great if you could clarify this fundamental
>>> issue.
>>>
>>> Many thanks
>>> Abhimanyu
>>>
>>>
>>> . list in 1
>>>
>>>     +--------------------------------------------------------------------------------------------------------------------+
>>>  1. |        var1 |        var2 |         var3 |         var4 | var5
>>> | var6 | var7 | var8 | var9 | var10 | var11 | var12 |
>>>     | Series Code | Series Name | Country Code | Country Name | 2000
>>> | 2001 | 2002 | 2003 | 2004 |  2005 |  2006 |  2007 |
>>>     |---------------------------------------------------------+----------------------------------------------------------|
>>>     |                          var13                          |
>>>                   var14                           |
>>>     |                           2008                          |
>>>                    2009                           |
>>>     +--------------------------------------------------------------------------------------------------------------------+
>>>
>>> On Thu, Aug 25, 2011 at 10:35 AM, Nick Cox <njcoxstata@gmail.com> wrote:
>>>> Already answered, but not correctly. You could e.g. use the first word
>>>> of the first value. This works:
>>>>
>>>> . l
>>>>
>>>>     +------------------------------+
>>>>     | var1   var2             var3 |
>>>>     |------------------------------|
>>>>  1. | Frog   Toad   Venomous snake |
>>>>  2. |    1      2                3 |
>>>>     +------------------------------+
>>>>
>>>> . renvars , map(`=word("@", 1)')
>>>>
>>>> . l
>>>>
>>>>     +------------------------------+
>>>>     | Frog   Toad         Venomous |
>>>>     |------------------------------|
>>>>  1. | Frog   Toad   Venomous snake |
>>>>  2. |    1      2                3 |
>>>>     +------------------------------+
>>>>
>>>> Nick
>>>>
>>>> On Thu, Aug 25, 2011 at 9:25 AM, Abhimanyu Arora
>>>> <abhimanyu.arora1987@gmail.com> wrote:
>>>>> I caught the mistake, thanks to -set trace on-. 'Code' is the second
>>>>> word of my observation of the first variable and of course a variable
>>>>> name has to be single worded. But my question on possibility of using
>>>>> Nick's -renvars- remains.
>>>>> Best regards
>>>>> Abhimanyu
>>>>>
>>>>>
>>>>> On Thu, Aug 25, 2011 at 10:07 AM, Abhimanyu Arora
>>>>> <abhimanyu.arora1987@gmail.com> wrote:
>>>>>> Good morning statalist
>>>>>> I would like to rename my variables var1-var14 to the corresponding
>>>>>> values from the first observation.
>>>>>> I followed the post on
>>>>>> http://www.stata.com/statalist/archive/2004-07/msg00009.html and
>>>>>> modified it for my purpose.
>>>>>>
>>>>>> but I got this error
>>>>>>
>>>>>> . forvalues k = 1/14  {
>>>>>>  2.   local newname  = var`k'[1]
>>>>>>  3.   ren var`k'  `newname'
>>>>>>  4. }
>>>>>>
>>>>>> Code not allowed
>>>>>>
>>>>>> Also is it posible to store the values of an observation in a macro?
>>>>>> Perhaps I could then use Nick Cox's -renvars-?
>>>>>>
>>
>
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>



-- 
Matthew White
Data Coordinator
Innovations for Poverty Action
101 Whitney Avenue, New Haven, CT 06510 USA
www.poverty-action.org

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