From Martin Maechler <maechler@stat.math.ethz.ch>  Fri Aug 25 17:57:50 2000
From: Martin Maechler <maechler@stat.math.ethz.ch> (Martin Maechler)
Date: Fri, 25 Aug 2000 18:57:50 +0200 (CEST)
Subject: [Rd] Re: plot.function documentation (was ".. too large alpha ..")
In-Reply-To: <39a683e6.3864125@fisher.stats.uwo.ca>
References: <200008251320.PAA05152@pubhealth.ku.dk>
 <39a683e6.3864125@fisher.stats.uwo.ca>
Message-ID: <14758.42382.735308.898057@gargle.gargle.HOWL>

>>>>> "Duncan" == Duncan Murdoch <murdoch@stats.uwo.ca> writes:

    Duncan> On Fri, 25 Aug 2000 15:20:10 +0200 (MET DST), Martin Maechler wrote in
    Duncan> message <200008251320.PAA05152@pubhealth.ku.dk>:

    >> Look at
    >> 
    >>> plot(function(x)    dbeta(x, 534,646, log = TRUE), n = 1001)

    Duncan> I never knew that plot could take a function!  
well..

    Duncan> Could I make some suggestions?
sure... no promisses though ;-)

    Duncan> 1.  It should be mentioned more prominently in the documentation.
    Duncan> Since functions aren't a class, I scanned over the list of plot
    Duncan> methods without ever noticing that functions were mentioned there.
    Duncan> I'd suggest modifying the description of parameter x to read:

    Duncan> x: the coordinates of points in the plot. Alternatively, a
    Duncan> single plotting structure, function or R object with a `plot' method
    Duncan> can be provided.

ok, done, thank you.
    Duncan> 2.  If xlim is specified and from and to aren't, the from and to
    Duncan> values should default to xlim[1] and xlim[2], not 0 and 1.  

good idea,
and easy to implement...  
I would have it as

  \item{xlim}{numeric of length 2; if specified, it replaces \code{from}
              and \code{to}.}

(and not give a warning if someone uses  xlim  *and* e.g. `from').

    Duncan> 3.  The help for plot.function says:

    Duncan> "This used to be a quick hack which seems to serve a useful
    Duncan> purpose, but can give bad results for functions which are not
    Duncan> smooth."

    Duncan> That doesn't read right:  it makes me ask, "If it used to be a quick
    Duncan> hack, what is it now?"  I'd suggest:
yes..
    Duncan> "This function was a quick hack which seems to serve a useful
    Duncan> purpose, but it can give bad results for functions which are not
    Duncan> smooth."

"This" was now really implying  both  curve()  and plot.function()  ...

Could I just add one word, "now", to make it

>>    "This used to be a quick hack which now seems to serve a useful purpose,
>>                                        ===
>>     but can give bad results for functions which are not smooth."

--
Thank you,
Martin
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[Rd] Re: plot.function documentation (was ".. too large alpha ..")
Martin Maechler