R help - Jun 2015 - Mean error message missing

Dear list,

I found an odd behavior of the mean function; it is allowed to do 
something that you probably shouldn't:
If you calculate mean() of a sequence of numbers (without declaring them 
as vector), mean() then just computes mean() of the first element. Is 
there a reason why there is no warning, like in sd for example?

Example code:
mean(1,2,3,4)
sd(1,2,3,4)

Best regards
Christian

On Mon, 8 Jun 2015, Christian Brandst?tter wrote:
> Dear list,
>
> I found an odd behavior of the mean function; it is allowed to do something
> that you probably shouldn't:
> If you calculate mean() of a sequence of numbers (without declaring them as
> vector), mean() then just computes mean() of the first element. Is there a 
> reason why there is no warning, like in sd for example?
mean() - unlike sd() - is a generic function that has a '...' argument 
that is passed on to its methods. The default method which is called in 
your example also has a '...' argument (because the generic has it) but 
doesn't use it.
> Example code:
> mean(1,2,3,4)
> sd(1,2,3,4)
>
> Best regards
> Christian
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

Thank you for the explanation.
But if you take for instance plot.default(), being another generic 
function, it would not work like that:
plot(1,2,3,4), only plot(1,2) is accepted.


 From R-help (Usage):
## Default S3 method:
mean(x, trim = 0, na.rm = FALSE, ...)

What is puzzling, is that apparently na.rm (and trim, which is indicated in the
help) is accepting numeric values.
mean(c(1,NA,10),10,TRUE)
mean(c(1,NA,10),10,FALSE)

This should give at least a warning in my opinion.

mean(c(1,NA,10),10,200)



On 08/06/2015 09:27, Achim Zeileis wrote:
> On Mon, 8 Jun 2015, Christian Brandst?tter wrote:
>
>> Dear list,
>>
>> I found an odd behavior of the mean function; it is allowed to do 
>> something that you probably shouldn't:
>> If you calculate mean() of a sequence of numbers (without declaring 
>> them as vector), mean() then just computes mean() of the first 
>> element. Is there a reason why there is no warning, like in sd for 
>> example?
>
> mean() - unlike sd() - is a generic function that has a '...'
argument
> that is passed on to its methods. The default method which is called 
> in your example also has a '...' argument (because the generic has
it)
> but doesn't use it.
>
>> Example code:
>> mean(1,2,3,4)
>> sd(1,2,3,4)
>>
>> Best regards
>> Christian
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide 
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>

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