Re: [R] all(logical(0)) and any(logical(0))

[Patrick Burns]

I suspect that some people still might not have caught why
the behavior is a good thing.
We want

any(c(A, B))

to give the same answer as

any(A) || any(B)

This should be the behavior even if all of the elements are
in one of the vectors.
This actually is useful in coding, though I can't think of any
specific instances at the moment.
Patrick Burns

Burns Statistics
[EMAIL PROTECTED]
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http://www.burns-stat.com
(home of S Poetry and "A Guide for the Unwilling S User")
Douglas Bates wrote:

"Liaw, Andy" <[EMAIL PROTECTED]> writes:

 

I wrote:

   

I was bitten by the behavior of all() when given logical(0):  
It is TRUE!
(And any(logical(0)) is FALSE.)  Wouldn't it be better to 
return logical(0)
in both cases?
     

I guess the behavior is consistent with:

   

prod(numeric(0))
     

[1] 1
   

sum(numeric(0))
     

[1] 0

but why?
   

The operation applied to a zero-length vector returns the identity
element of the operator.  The identity element of * is 1, of + is 0,
of & is TRUE and of | is FALSE.
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