Re: [Rd] inaccuracy in qbinom with partial argument matching

From: Petr Savicky <savicky_at_cs.cas.cz>
Date: Fri, 29 Jun 2007 11:04:06 +0200

> > ## partial argument matching:
> > qbinom(p0 , s = 3, p = 0.25) ## 1 ???
> > qbinom(p0-0.05, s = 3, p = 0.25) ## 1 ???
> > qbinom(p0-0.06, s = 3, p = 0.25) ## 0 o.K.
> >
> > Unfortunately I have no I idea how to fix this.
>
> You use a call that specifies your intentions accurately. This is not
> 'partial argument matching': 'p' is an exact match to the first argument
> of
>
> > args(qbinom)
> function (p, size, prob, lower.tail = TRUE, log.p = FALSE)
>
> and that is how argument matching in R is documented to work.
>
> The 'inaccuracy' is in the diagnosis: please see the FAQ.
 

Let me add an explanation, why
  qbinom(p0 , s = 3, p = 0.25) does not produce an error message about missing "prob" argument: Since "size" and "p" arguments are given, p0 is used for the third argument and not for the first.

Although the behavior is logical, it may not be immediately clear. I do not see this case explicitly in FAQ or R-intro.pdf 10.3.

Petr.



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