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Re: st: identifying variables
From
Abhimanyu Arora <[email protected]>
To
[email protected]
Subject
Re: st: identifying variables
Date
Mon, 9 Apr 2012 11:30:02 +0200
That's exactly what I needed to understand. Thanks a lot indeed, Nick.
Cheers
Abhimanyu
On Mon, Apr 9, 2012 at 9:57 AM, Nick Cox <[email protected]> wrote:
> You have provided yet another example of a problem in which -strpos()-
> offers a simple alternative to -regexm()-.
>
> That aside, your syntax is looking for the string "real" in the
> _variable names_ themselves, for which
>
> . findname *real*
>
> would be a more obvious syntax, and indeed -describe *real*- would
> work fine. Stata has a similar distinction in all string and regular
> expression functions between looking in a string variable strvar and
> looking in a variable name "varname".
>
> . l in 1
>
> +-------------------------------------------+
> | foo bar bazz y x |
> |-------------------------------------------|
> 1. | reality surreal unreal 42 3.14159 |
> +-------------------------------------------+
>
> . findname in 1, all(strpos(@, "real"))
> foo bar bazz
>
> . findname in 1, all(regexm(@, "[real]"))
> foo bar bazz
>
> . findname in 1, all(regexm(@, "real"))
> foo bar bazz
>
> @ is the default generic varname. -placeholder()- lets you specify an
> alternative. You only need to specify "@" for searching the variable
> names, but as above there are easier ways to do that.
>
> Nick
>
> On Mon, Apr 9, 2012 at 3:50 AM, Abhimanyu Arora
> <[email protected]> wrote:
>
>> I need to identify the variables for which the first observation
>> contains the string "real".
>> I used Nick Cox's -findname- from the SSC (updated 27 February 2012)
>> in the following command.
>>
>> findname var1-var56 in 1,all(regexm("@","real+")) loc (varnames)
>>
>> But since -return list- comes up empty, something is amiss, perhaps in
>> the use of the regular expression. May I also request some clarity in
>> understanding of the role played by a "placeholder" in -findname-? As
>> I see it, a generally character designated as a "placeholder" is
>> supposed to take on supplied values—string or numerals. Or in other
>> words, how would stata read the "@" in the above command?
>>
>
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