[R] all(logical(0)) and any(logical(0))
dmurdoch at pair.com
Thu Apr 15 17:17:21 CEST 2004
On Thu, 15 Apr 2004 10:40:41 -0400, "Liaw, Andy" <andy_liaw at merck.com>
>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?
As Rolf said, this behaviour makes sense.
>The problem surfaced because some un-named individual called randomForest(x,
>y, xtest, ytest,...), and gave y as a two-level factor, but ytest as just
>numeric vector. I thought I check for that in my code by testing for
>if (!all(levels(y) == levels(ytest))) stop(...)
You should fix this by having
y <- as.factor(y)
ytest <- as.factor(ytest)
somewhere earlier in your code, since your code assumes that they are
both factors, but doesn't enforce that in its input checks.
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