[R] jitter function when length(x) = 1

[Rui Barradas]

Hello,

You can see the code for jitter by typing its name at the prompt.
Inline.

Em 09-10-2014 18:19, Ingrid Charvet escreveu:
> Hello,
>
> A quick question relating to the documentation of the jitter function:
> http://127.0.0.1:15714/library/base/html/jitter.html
>
> jitter(x, factor = 1, amount = NULL)
>
> "If amount is NULL (default), we set a <- factor * d/5 where d is the smallest difference between adjacent unique (apart from fuzz) x values."
>
> Therefore if length(x) = 1, then d = 0, which means jitter(x) should be equal to x?
> Which is not the case, i.e.
>
>> x <- 1
>> jitter(x)
> [1] 0.9842914
>
> So how does jitter deals with this situation? Does it assume d = x?

It doesn't assume, it computes range(x) and acts accordingly. The code 
lines are

     z <- diff(r <- range(x[is.finite(x)]))
     if (z == 0)
         z <- abs(r[1L])

It has the effect of setting z to x. Try running them. (And with x <- 2 
to see the difference.)

Hope this helps,

Rui Barradas
>
> Thanks
> IC
>
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