On 19/05/2017 8:48 AM, S Ellison wrote:
SQL, for example, generally takes the view that any
expression involving 'missing' is 'missing'.
Well, then SQL gets it wrong.
Well, that's a view. But paraphrasing an R Turner from a few lines away in the
same email:
One should be very, very circumspect about presuming to know better than
SQL
It's a choice. I understand and respect R's. But I can also understand why
someone might have expected something different.
You're right about SQL. But for R, it's pretty simple to read the help
page on NA, and it is quite explicit about this:
"Logical computations treat NA as a missing TRUE/FALSE value, and so may
return TRUE or FALSE if the expression does not depend on the NA operand."
I'm surprised nobody on this thread has quoted that before.
Duncan Murdoch
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