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# Re: st: using value of one variable to read value of specific other variable out of a list of variables

 From "Christian Holz (Stata list)" To statalist@hsphsun2.harvard.edu Subject Re: st: using value of one variable to read value of specific other variable out of a list of variables Date Mon, 9 May 2011 14:14:44 -0400

```Hi Arne,

generate z=.
replace z=x1 if y==1
replace z=x2 if y==2
replace z=x3 if y==3

or more generically (ie if there are more than 3 possibilities)

generate z=.
foreach n of numlist 1/3 {
replace z=x`n' if y==`n'
}

Cheers,
Christian

On Mon, May 9, 2011 at 1:30 PM,  <arne.weiss@uni-erfurt.de> wrote:
> Dear everyone,
>
> I am sure there is some obvious solution that I am not seeing, but I
> couldn't figure it out:
> I want to create a variable (z) that contains the value from one variable
> out of a list of variables (say x1 - x3) depending on the valuable of
> another variable (y). The list of variables is a) named in a way that the
> value of y could be used to refer to the correct name of the variable and b)
> ordered so that the value of y could also be used a locational reference (as
> the offset command does in Excel). I don't think b) could work in STATA, but
> I couldn't find a solution for a) either. See below an example. Therein, z
> in the first row is supposed to be 1 and in the second row 5 (if y = 2, z is
> supposed to have the value of x2).
>
> x1    x2    x3    y
> 1    2    3    1
> 0    5    4    2
>
> Here is the closest I came towards a solution:
> local a = y
> gen z = x`a'
>
> This command, however, only does half the job as the value of the local a is
> not being rest for every row. I would be very happy for any advice.
>
> Arne
>
> --
> Dr. Arne Robert Weiß
> University of Erfurt Nordhäuser Str. 63, D-99089 Erfurt Tel: +49 361 737
> 4522
> Fax: +49 361 737 4569
> http://www.uni-erfurt.de/mikrooekonomie/lehrstuhlteam/dr-arne-weiss
> http://arneweiss.blogspot.com
> *
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```