[Rd] I wish xlim=c(0, NA) would work. How about I send you a patch?

Duncan Murdoch murdoch.duncan at gmail.com
Mon Apr 16 21:15:31 CEST 2012

On 12-04-16 2:26 PM, William Dunlap wrote:
> plot(1:10, xlim=c(10,1)) reverses the x axis.
> If we allow plot(1:10, xlim=c(5,NA)), which
> direction should it go?    Would this require new
> parameters, {x,y}{min,max} or new paremeters
> {x,y}{axisDirection}?

I'd rather not add another parameter.  So if I were to implement this, 
I'd probably choose Paul's original suggestion.  If someone wants c(5, 
NA) to mean c(5, min(data)) rather than c(5, max(data)) they'd need to 
code it explicitly.

Duncan Murdoch

> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com
>> -----Original Message-----
>> From: r-devel-bounces at r-project.org [mailto:r-devel-bounces at r-project.org] On Behalf
>> Of Duncan Murdoch
>> Sent: Monday, April 16, 2012 11:14 AM
>> To: Paul Johnson
>> Cc: R Devel List
>> Subject: Re: [Rd] I wish xlim=c(0, NA) would work. How about I send you a patch?
>> On 12-04-16 1:52 PM, Paul Johnson wrote:
>>> I'm looking for an R mentor.  I want to propose a change in management
>>> of plot options xlim and ylim.
>> Your suggestion sounds reasonable, but because plot limits are such a
>> commonly used parameter, it would have to be done quite carefully.  The
>> questions I'd ask before implementing it are:
>>    - Are there other locations besides plot.default where xlim and ylim
>> are specified?  I'd like to have them updated consistently.
>>    - Are there any conflicting uses of NA for a limit in published packages?
>>    - Which package authors would need to be told about this change, so
>> they could make a compatible change?
>>    - Where does it need to be documented?
>> Duncan Murdoch
>>> Did you ever want to change one coordinate in xlim or ylim? It happens
>>> to me all the time.
>>> x<- rnorm(100, m=5, s=1)
>>> y<- rnorm(100, m=6, s=1)
>>> plot(x,y)
>>> ## Oh, I want the "y axis" to show above x=0.
>>> plot(x,y, xlim=c(0, ))
>>> ##Output: Error in c(0, ) : argument 2 is empty
>>>    plot(x,y, xlim=c(0,NA ))
>>> ## Output: Error in plot.window(...) : need finite 'xlim' values
>>> I wish that plot would let me supply just the min (or max) and then
>>> calculate the other value where needed.
>>> It is a little bit tedious for the user to do that for herself.  The
>>> user must be knowledgeable enough to know where the maximum (MAX) is
>>> supposed to be, and then supply xlim=c(0, MAX). I can't see any reason
>>> for insisting users have that deeper understanding of how R calculates
>>> ranges for plots.
>>> Suppose the user is allowed to supply NA to signal R should fill in the blanks.
>>> plot(x,y, xlim=c(0, NA))
>>> In plot.default now, I find this code to manage xlim
>>>      xlim<- if (is.null(xlim))
>>>           range(xy$x[is.finite(xy$x)])
>>> And I would change it to be something like
>>>      ##get default range
>>>      nxlim<- range(xy$x[is.finite(xy$x)])
>>>      ## if xlim is NULL, so same as current
>>>       xlim<- if (is.null(xlim)) nxlim
>>> ## Otherwise, replace NAs in xlim with values from nxlim
>>>       else xlim[ is.na(xlim) ]<- nxlim[ is.na(xlim) ]
>>> Who is the responsible party for plot.default.  How about it?
>>> Think of how much happier users would be!
>>> pj
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