Re: st: Manipulation of string variable using -regexm-

[Federico Belotti <f.belotti@gmail.com>]

Dear Herve

my suggestion is to use the command -screening-, a Stata's user-written string variables exploring and recoding tool.
You need to search and install it using

findit screening

Once installed, the syntax you are looking for to obtain a new numeric variable equal to 0 if not star, 1 if only *, 2 if *- and 3 if *+ is the following

screening, source(CurrRtg, upper) key(end "\*" end "\*-" end "\*\+" end "[A-Z]") new(mark, numeric) recode(1 "1" 2 "2" 3 "3" 4 "0")

where
	
	1) the option -source()- specifies the source variable that have to be recoded (note the suboption -upper- which allows to perform a case-insensitive match (uppercase));
	2) the option -key()- specifies the keywords you are looking for (in this case represented by regular expressions);
	3) the option -new()- specifies the name of the new variable to be created (in this case, I called it "mark". Note the suboption -numeric- that allows to get the newly created variable as a numeric variable);
	4) the option -recode()- specifies the user-defined coding scheme following the keywords order.

See -help screening- for more details.

Hope this helps.
Federico


On Oct 11, 2013, at 6:40 PM, STOLOWY, Herve wrote:

> Dear Statalisters:
> 
> Using Stata 12.1, I want to extract a portion of a string variable using
> regular expressions, i.e. -regexs- and -regexm-.
> 
> My string variable has different possible values. Example:
> 
> A
> A *
> A *-
> A *+
> B
> B *
> B *-
> B *+
> etc.
> 
> I would like to get a variable with the content filled with the * or *- or
> *+ or with this type of coding:
> 
> 0 if not star
> 1 if only *
> 2 if *-
> 3 if *+
> 
> The * or *- or *+ always appear at the end on the value.
> 
> I tried the following syntax:
> 
> gen var_star =3D regexs(0) if(regexm(CurrRtg, "\*" "\*+" "\*-"))
> 
> Unfortunately, I get a * in all cases there is a * included in the value,
> but I do not get the *- or *+.
> 
> I have difficulties with the syntax of -regexm-.
> 
> There is maybe another way to get the same result.
> 
> Best regards
> 
> Herve Stolowy
> *
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-- 
Federico Belotti, PhD
Research Fellow
Centre for Economics and International Studies
University of Rome Tor Vergata
tel/fax: +39 06 7259 5627
e-mail: federico.belotti@uniroma2.it
web: http://www.econometrics.it


*
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