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

[arne.weiss@uni-erfurt.de]

Nick Cox schrieb:
> gen z = cond(y == 1, x1, cond(y == 2, x2, x3)) 
>
> Nick 
> n.j.cox@durham.ac.uk 
>
> arne.weiss@uni-erfurt.de
>
> 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.
>
>
> *
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>   
Thanks, Nick. That is already much better than repeated if qualifiers. 
However, my actual set of variables is longer than 3 variables, and I 
have the same type of problem several times in my data-set. Before doing 
it "brute force", would you happen to know a more "elegant" solution? 
Thanks already anyway!
Best
Arne

--
Dr. Arne Robert Weiß
University of Erfurt 
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*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/