On 27/10/2012 10:16, Jinsong Zhao wrote:
Hi there,
In the following example, sd() can be applied to a character vector.
However, mean() can not be run in a similar way. Why?
I have read sd() man page, however, I don't find information about that
behavior.
Well, it is there:
x: a numeric vector or an R object which is coercible to one by
‘as.vector’.
> as.vector(x, 'numeric')
[1] 1 2 3 4 5 6 7 8 9 10
And it is different from mean() because that is generic and allows many
other forms of input, whereas for sd() one knows what to coerce to.
> x <- as.character(1:10)
> sd(x)
[1] 3.02765
> mean(x)
[1] NA
Warning message:
In mean.default(x) : argument is not numeric or logical: returning NA
Regards,
Jinsong
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