Re: repost: -cond()- function

[Richard Williams <Richard.A.Williams.5@nd.edu>]

At 11:20 AM 1/1/2004 -0500, Michel Camus wrote:
> I experience the same "problem" as you do, Paul.
> I believe it has to do with "binary logic". The logical condition ("chol") 
> always evaluates to 0 or 1, and nothing else,  it  never evaluates to "9" 
> even if the original variable does have "9" as one value. The same happens 
> even if your missing values in "chol" were already coded as "." See 
> http://www.stata.com/support/faqs/data/values.html  by W. Gould on 
> "Logical expressions and missing values". The way to have missing values 
> is tocondition your expression as follows :
However, the docs say this about the cond command:

"cond(x,a,b,c) returns a if x evaluates to true (not 0), b if x evaluates 
to false (0), and c if x evaluates to missing (.)."

So, it seems it should work (assuming his md value is ., or .a, or .b, 
etc.; if he is trying to use 9 as an md value, that won't work, he has to 
be using one of Stata's md values).  Plus, it did work for me!  So, my 
guess is that either (a) he is using some earlier version of Stata which 
does not support this variation of the cond command, or (b) he's not using 
one of Stata's md values, e.g. he is using 9 for md when Stata wants ., .a, 
etc.

In any event, it only takes one additional line of code to fix, but it 
seems like the command as originally written should work except under the 
conditions I have just mentioned.



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