[R] Unspecified [upper] xlim/ylim?

[(Ted Harding)]

On 15-Jun-10 16:01:24, William Dunlap wrote:
>> -----Original Message-----
>> From: r-help-bounces at r-project.org 
>> [mailto:r-help-bounces at r-project.org] On Behalf Of 
>> Ted.Harding at manchester.ac.uk
>> Sent: Tuesday, June 15, 2010 8:49 AM
>> To: r-help at stat.math.ethz.ch
>> Subject: [R] Unspecified [upper] xlim/ylim?
>> 
>> Greetings!
>> I would like to be able to specify a fixed (say) lower limit
>> for plotting, while leaving the upper limit "floating, when
>> plotting. The context is that the maximum in the data to be
>> plotted is unpredictable, being the consequence of a simulation,
>> whereas I know that it cannot be less than (say) 0; and I want
>> to fix the lower limit at 0 in any plot, leaving the upper limit
>> to be assigned by plot() as a result of the computed values.
>> 
>> I know I can do this by determining the max() of the data, and
>> then computing a "Ymax" to put in (say) ylim = c(0,Ymax). However,
>> for certain reasons, I would prefer not to have to do this.
>> (And it's just a preference ... ).
>> 
>> Whereas one can leave the whole issue of setting both plotting
>> limits to plot(), by not specifying ylim (or xlim), or one can
>> explcitily specify both the upper and lower limits by (say)
>> ylim=c(Ymin,Ymax), there seems to be no way of fixing one and
>> leaving the other floating so that plot() would do its own thing.
>> 
>> ylim requires two numbers to be given. Things like ylim=c(0,)
>> or ylim=c(0,NA) would generate an error.
> 
> Currently ylim=c(yValueAtBottomOfPlot, yValueAtTopOfPlot), not
> c(yMin,yMax).  E.g., ylim=c(10,0) means to reverse the y axis,
> with 0 at the top and 10 at the bottom.  Putting an NA into
> ylim seems attractive but doesn't it run into problems because
> ylim doesn't mean c(yMin,yMax)?
> 
> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com  
> 
>> 
>> Am I chasing a phantom? Or is there a way?
>> Thanks
>> Ted.

Sorry, Bill, but you've misunderstood what I mean by "Ymin" and "Ymax".
As explained, these are notations for values which I either compute,
or choose, to put in as the arguments in ylim=c(... , ...). YMin and
Ymax would be such as to ensure that the range of the axis included
at least the range (Ymin,Ymax) (or, depending on the choice, possibly
to exclude certain values from the plot).

So, indeed, ylim does mean c(Ymin,Tmax).

Ted.

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E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
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Date: 15-Jun-10                                       Time: 18:11:29
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