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

[Nick Cox <n.j.cox@durham.ac.uk>]

For a longer list of x variables, you could do this: 

gen z = . 

qui forval j = 1/15 { 
	replace z = x`j' if y == `j' 
} 

Nick 
n.j.cox@durham.ac.uk 


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox
Sent: 09 May 2011 18:35
To: 'statalist@hsphsun2.harvard.edu'
Subject: st: RE: using value of one variable to read value of specific other variable out of a list of variables

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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