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Re: st: renaming variables from first observation


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: renaming variables from first observation
Date   Thu, 25 Aug 2011 11:04:27 +0100

Yes indeed.

-strtoname()- arrived in Stata long after even the last update of
-renvars-, but that doesn't rule out anything.

renvars, map(strtoname(@[1]))

would I guess be the recipe to try, or

forval j = 1/14  {
     rename var`j' `=strtoname(var`j'[1])'
}

Nick

On Thu, Aug 25, 2011 at 10:57 AM, Matthew White
<mwhite@poverty-action.org> wrote:

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

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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>

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