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Re: st: "If" in a local variable


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: "If" in a local variable
Date   Tue, 30 Nov 2010 09:03:45 +0000 (GMT)

--- On Nov 29, 2010, at 8:39 PM, Laurie Molina wrote:
> > I want to set the value of a local variable,
> > conditional of the value of some other variable, but
> > i think the option "if" is not availabe for a local
> > variable.
> > What i would like to do is the following:
> > local a= 1 if `b' > `c'
> > local a= 2 if `b' < = `c'

--- On Tue, 30/11/10, Eric Booth wrote:
> You can use the  -if- command instead of the "if"
> qualifier.  See -help ifcmd-.   You probably want
> this:
>     
>      if `b' > `c'  local a= 1
<snip>

An alternative to Eric's solution is to use the 
-cond()- function:

local a = cond(`b' > `c', 1, 2)

Hope this helps,
Maarten

PS Just a clarification on terminology:

Variables in Stata-speak are columns in a data-matrix.
So `a' is not a "local variable", as it is not a column
in a data-matrix. Instead it is a "local macro", often
abreviated as a "local". Options are things that are 
placed after the comma in a command, so -if- is not 
an option. It is called a qualifier if it appears
at the end of a command (but before the comma) and a 
command when it appears at the front. 

--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://www.maartenbuis.nl
--------------------------


      

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