[R] Plotmath bug or my misunderstanding?

Sun May 13 20:45:35 CEST 2012

Peter/David:

Yes, I think this is the general approach for multiple lines in
plotmath expressions. For future reference, a simple canonical example
is:

exl <- list(quote(sigma), "tau",quote(beta))
plot(0:1,0:1,type="n",axes=FALSE)
text(do.call(expression,exl),x=.5,y=seq(.4,.6,by=.1),cex=2)

The points to note are:

1. The plotmath expressions, but not quoted character strings,  in the
list have to be protected from evaluation by quote() (or bquote if
variable values are to be substituted in them);

2. The individual components/lines have to be positioned manually via
x and y; there is no newline ("\n") capability, since plotmath is
"drawing" the expressions.

3. atop()  is NOT the right way to do this.

Thanks to you both for clarifying this for me.

Best,
Bert

On Sun, May 13, 2012 at 9:45 AM, David Winsemius <dwinsemius at comcast.net> wrote:
>
> On May 13, 2012, at 10:43 AM, Bert Gunter wrote:
>
>> Peter/David:
>>
>> 1. For some reason, I didn't see Peter's reply on r-help.
>>
>> 2. To Peter: Aha!!
>> Let me play this back to you. In
>>
>> text(1,1,labels=expression(atop(atop(sigma,"some text"),"another
>> level")),cex = 2)
>>
>> The (outer) whole atop() specification is allocated twice the amount
>> of space that would be required for the current font size, cex =1.
>> Then each of the top and bottom is allocated the amount of space
>> needed within this cex = 2 space. For the inner atop to fit within
>> that allocated amount of space, its top and bottom must get smaller,
>> of course. N'est-ce pas?
>>
>> This makes sense to me!  My misunderstanding is thinking that cex
>> applied to the individual text components, not the entire expression.
>> Enlightenment much appreciated.
>>
>> 3. However, this now begs the question of how to keep all text and
>> symbols the same size, which is really what the OP really wanted (a
>> way to emulate multiple lines). I'll fool around with this to see what
>> I come up with now that I'm enlightened -- or see if you or David come
>> up with something clever.
>
>
> Any cleverness I exhibit on these pages is generally ascribable to my
> R-betters. When faced with a request like this, I just fire up Google and
> generally find an answer from Lumley, Grothendieck, Ligges, or in this case,
> Schwartz (from an rhelp post in 2009). This was the first hit that wasn't a
> link to R documentation with a search on "multiple lines expression plotmath
> r"
>
> # values to pull from using bquote
>  X= 2.3
> Y= 5.6
> txtList <- list("Line # 1",
>     "Longer line #2",
>      bquote(X == .(X)),
>     "and",
>      bquote(The~value~of~Y == .(Y)))
>
> plot(1,type="n", xaxt='n', yaxt='n', ann=FALSE)
> text(1.2, seq(1.2, 1.1, len=5) , labels=do.call(expression, txtList))
>
> I think this is a fairly generally strategy but I'm certainly willing to
> take a crack at further modifications if desired.
>
> --
> david.
>
>>
>>
>> Cheers,
>> Bert
>>
>>
>>
>> On Sat, May 12, 2012 at 9:27 PM, David Winsemius <dwinsemius at comcast.net>
>> wrote:
>>>
>>>
>>> On May 12, 2012, at 6:27 PM, Peter Ehlers wrote:
>>>
>>>> Hi Bert,
>>>>
>>>> I think the 'cex=' argument applies to the outermost 'atop()'.
>>>> It then applies that size specification to each of the two
>>>> components of the atop(a,b). If one of the components is itself
>>>> another atop(a,b), then the individual parts are sized downward
>>>> to produce the required cex for the unit.
>>>>
>>>> As for the 'cex=1:2' specification, only the first value is used.
>>>
>>>
>>>
>>> Isn't there also a 0.67 factor being applied to whatever was the
>>> "outside"
>>> size prior to being used for the atop arguments? So the inner atop
>>> arguments
>>> get that applied twice if I understand correctly.
>>>
>>> text(1,1,labels=expression(atop(
>>>              atop("top level one", "top level two"),
>>>              "another level")
>>>    ) )
>>>
>>>
>>> I did notice that the cr-linefeed (perhaps unintentionally being inserted
>>> by
>>> a mail client) seemed to be "working" at least on my Mac :
>>>
>>> plot(1,1)
>>> text(1,1,labels=expression("another
>>> level")
>>>    )
>>>
>>> Whereas it is well known that "\n" will appear as two characters, \n, and
>>> not be interpreted as a special.
>>> --
>>> David
>>>>
>>>>
>>>>
>>>> Cheers,
>>>> Peter Ehlers
>>>>
>>>> On 2012-05-12 14:05, Bert Gunter wrote:
>>>>>
>>>>>
>>>>> This is a followup to a recent post on using atop() to obtain
>>>>> multiline expressions.
>>>>>
>>>>> My reading of the plotmath docs makes it clear that issuing (in base
>>>>> graphics) the specification
>>>>>
>>>>> par(cex = 2)
>>>>>
>>>>> doubles symbols and regular text in subsequent plotmath expressions.
>>>>> However, it is unclear to me what specifying cex _within_ the
>>>>> annotation function using plotmath should do, and the following seems
>>>>> to want to have it both ways: ignore/obey )or maybe recycle?)
>>>>>
>>>>> plot(1,type="n", xaxt='n', yaxt='n', ann=FALSE)
>>>>>  text(1,1,labels=expression(atop(sigma,"some text")),cex = 2)
>>>>> ## obeys the cex specification in symbols and text
>>>>>
>>>>> HOWEVER
>>>>>
>>>>> plot(1,type="n", xaxt='n', yaxt='n', ann=FALSE)
>>>>>  text(1,1,labels=expression(atop(atop(sigma,"some text"),"another
>>>>> level")),cex = 2)
>>>>> ## ???
>>>>>
>>>>> For even more fun, try:
>>>>>
>>>>> plot(1,type="n", xaxt='n', yaxt='n', ann=FALSE)
>>>>>  text(1,1,labels=expression(atop(atop(sigma,"some text"),"another
>>>>> level")),cex = 1:2)
>>>>> ##????
>>>>>
>>>>> So I confess to being flummoxed. Enlightenment would be much
>>>>> appreciated.
>>>>>
>>>>> Cheers,
>>>>> Bert
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide
>>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>>>
>>> David Winsemius, MD
>>> West Hartford, CT
>>>
>>
>>
>>
>> --
>>
>> Bert Gunter
>> Genentech Nonclinical Biostatistics
>>
>> Internal Contact Info:
>> Phone: 467-7374
>> Website:
>>
>> http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
>
>
> David Winsemius, MD
> West Hartford, CT
>

-- 

Bert Gunter
Genentech Nonclinical Biostatistics

Internal Contact Info:
Phone: 467-7374
Website:
http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm