[R] scatter.smooth() line colour

[David Winsemius]

On Jun 22, 2012, at 1:50 PM, Martin Maechler wrote:

>
>> It's really not that difficult to fix with some simple changes to the
>> code:
>
>> scatter.smooth.col <-
>> function (x, y = NULL, span = 2/3, degree = 1, family =  
>> c("symmetric",
>>     "gaussian"), xlab = NULL, ylab = NULL, ylim = range(y, pred$y,
>>     na.rm = TRUE), evaluation = 50, ..., lcol, llty, llwd)
>> {
>>     xlabel <- if (!missing(x))
>>         deparse(substitute(x))
>>     ylabel <- if (!missing(y))
>>         deparse(substitute(y))
>>     xy <- xy.coords(x, y, xlabel, ylabel)
>>     x <- xy$x
>>     y <- xy$y
>>     xlab <- if (is.null(xlab))
>>         xy$xlab
>>     else xlab
>>     ylab <- if (is.null(ylab))
>>         xy$ylab
>>     else ylab
>>     pred <- loess.smooth(x, y, span, degree, family, evaluation)
>>     plot(x, y, ylim = ylim, xlab = xlab, ylab = ylab, ...)
>>     lines(pred$x, pred$y, col=lcol, lty=llty, lwd=llwd)
>>     invisible()
>> }
>
>> require(graphics)  # Not really sure why this is needed but it's in
>> the help page
>
> because the function builds on loess() and loess() is part of
> 'stats' and not 'graphics' (and because all of this is
> "historical" ..)
>
>> with(cars, scatter.smooth.col(speed, dist, lcol="red", llwd=3,  
>> llty=3))
>> # dotted thick smoothed line results
>
> Indeed, this is really trivial and one could argue
> "every" R user should be able to do something like the above.
>
> A slightly nicer solution --- which not every R user will be able to  
> do,
> but hopefully (;-) everyone reading R-help for a little while ---
> is to allow a *list* of more arguments, all passed to lines(),
> actually as Mark proposed {at the very end}, and to use
> do.call(lines, *)
>
> As a little exercise for you to see,
> I'll add  that to R-devel .. even though I wonder if its worth
> the extra work {{but then, as otherwise someone gets the idea to
>    	         file it in the bug tracker ..}}
> soon to be visible at
>   https://svn.r-project.org/R/trunk/src/library/stats/R/loess.R

The reason I added specific arguments was to prevent the points and  
the lines from necessarily being the same color. Likewise, I noted  
that the 'lwd' argument seemed to affect the points in a manner I  
found surprising, although it made sense when I thought about it a  
bit. After looking at plot.default and par's conventions about  
coloring parameters, I was going got suggest using 'col.pred' and  
'lwd.pred' as argument names that would get passed to line( ... col,  
lwd). Experimentation shows that the points do not get affected by  
'lty'.

-- 
David.
>
> Martin Maechler,
> ETH Zurich  (and R core)
>
>
>> -- 
>> David
>
>
>> On Jun 22, 2012, at 10:51 AM, Mark Payne wrote:
>
>>> Hi David,
>>>
>>> Thanks for the reply. I agree - it just seemed that it was something
>>> fairly obvious that was missing from an otherwise handy little
>>> function.... Would it be appropriate to file it as a "request for
>>> improvement" in the bug tracking system?
>>>
>>> Mark
>>>
>>> On 22 June 2012 16:30, David L Carlson - dcarlson at tamu.edu
>>> <+r-help+trevva+3b274928d0.dcarlson#tamu.edu at spamgourmet.com> wrote:
>>>> You are correct about scatter.smooth, but loess.smooth
>>>> (listed along with scatter.smooth on the same
>>>> help page) gives you the way to get what you want:
>>>>
>>>> x <- rnorm(25)
>>>> y <- rnorm(25)
>>>> plot(x, y)
>>>> lines(loess.smooth(x,y), col="red", lty=2, lwd=2)
>>>>
>>>> ----------------------------------------------
>>>> David L Carlson
>>>> Associate Professor of Anthropology
>>>> Texas A&M University
>>>> College Station, TX 77843-4352
>>>>
>>>>
>>>>> -----Original Message-----
>>>>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
>>>>> project.org] On Behalf Of r-help.20.trevva at spamgourmet.com
>>>>> Sent: Friday, June 22, 2012 6:04 AM
>>>>> To: r-help at r-project.org
>>>>> Subject: [R] scatter.smooth() line colour
>>>>>
>>>>> Hi,
>>>>>
>>>>> I really like the scatter.smooth() function - its extremeley  
>>>>> useful.
>>>>> However, as far as I understand it, there is no way to change the
>>>>> properties of the smoothing line e.g. col, lty, lwd. The
>>>>> scatter.smooth function accepts a ... argument, but these are not
>>>>> passed to the plotting function that actually plots the smoother -
>>>>> only to the function that plots the points. Could I please  
>>>>> therefore
>>>>> request that an argument be added to this function to give easier
>>>>> control over line properties? e.g. line.par=list()
>>>>>
>>>>> Best wishes,
>>>>>
>>>>> Mark Payne
>>>>>
>
>> David Winsemius, MD
>> West Hartford, CT
>

David Winsemius, MD
West Hartford, CT