>>>>> Viechtbauer, Wolfgang (NP) writes:
Thanks. Patches welcome :-)
Best
-k
>> -----Original Message-----
>> From: Kurt Hornik <kurt.hor...@wu.ac.at>
>> Sent: Friday, October 11, 2024 14:18
>> To: Viechtbauer, Wolfgang (NP) <wolfgang.viechtba...@maastrichtuniversity.nl>
>> Cc: r-devel <r-devel@r-project.org>
>> Subject: Re: [Rd] Error message when calling t.test() and aov() with a factor
>> variables
>>
>> >>>>> Viechtbauer, Wolfgang (NP) writes:
>>
>> > Hi all,
>> > Just noticed that the error that arises when calling t.test() with factors
>> could be a bit clearer:
>>
>> >> t.test(factor(c(3,1,2,4,3,5,4,5)), factor(c(2,1,2,3,4,5)))
>> > Error in var(x) : Calling var(x) on a factor x is defunct.
>> > Use something like 'all(duplicated(x)[-1L])' to test for a constant
>> > vector.
>> > In addition: Warning message:
>> > In mean.default(x) :
>> > argument is not numeric or logical: returning NA
>>
>> > Obviously, using factors as input is nonsense, but this might happen on
>> accident and then the error message could be a bit more on point. Similar for
>> aov():
>>
>> >> aov(factor(c(3,1,2,4,3,5,4,5)) ~ factor(c(2,1,2,2,2,1,2,1)))
>> > Call:
>> > aov(formula = factor(c(3, 1, 2, 4, 3, 5, 4, 5)) ~ factor(c(2,
>> > 1, 2, 2, 2, 1, 2, 1)))
>> > Error in levels(x)[x] :
>> > only 0's may be mixed with negative subscripts
>> > In addition: Warning messages:
>> > 1: In model.response(mf, "numeric") :
>> > using type = "numeric" with a factor response will be ignored
>> > 2: In Ops.factor(y, z$residuals) : '-' not meaningful for factors
>>
>> > Not a big deal and trying to catch all of the silly things users may
>> > do is of course impossible, but for this one adding a check that the
>> > (response) variable is actually numeric could be useful.
>>
>> Indeed.
>>
>> As always, the question is whether we want to give an error unless
>> is.numeric, or ensure via as.numeric?
> I would issue an error. Using as.numeric() could lead to totally nonsensical
> results, for example when:
> as.numeric(factor(c("low","high","mid")))
>> Best
>> -k
>>
>> > Best,
>> > Wolfgang
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