On Sep 16, 2012, at 2:58 PM, Peter Ehlers wrote:
> On 2012-09-16 08:32, David Winsemius wrote:
>>
>> On Sep 16, 2012, at 4:40 AM, peter dalgaard wrote:
>>
>>>
>>> On Sep 16, 2012, at 07:48 , David Winsemius wrote:
>>>
>>>>
>>>> On Sep 15, 2012, at 7:15 PM, mcg wrote:
>>>>
>>>>> Hello R-users,
>>>>>
>>>>> I would like to use subscript in chemical formulas for the different
>>>>> treatments in a boxplot.
>>>>> Fot title, xlab and ylab sub- and superscript is no problem, but for the
>>>>> different treatments of the following example I cannot get subscript.
>>>>>
>>>>> Example:
>>>>> weight <- c(6,5,7,2,7,3,9,4,2,7,8,9,2,3,4,5)
>>>>> treatments <- as.factor(rep(c('Control', 'P2O5','K2SO4','CaSO4'),4))
>>>>> data <- data.frame(treatments,weight)
>>>>> boxplot(data$weight~data$treatments)
>>>>>
>>>>> If I apply expression(P[2]...) I get "unimplemented type 'expression' in
>>>>> 'HashTableSetup' ".
>>>>> If there is a solution for this in base graphics or ggplot please let me
>>>>> know.
>>>>>
>>>>
>>>> ?plotmath
>>>> boxplot(data$weight~data$treatments, xaxt="n")
>>>> axis(1, 1:4, labels=expression(Control, P[2]*O[5], K[2]*SO[4], CaSO[4]) )
>>>>
>>>> I will admit that the need for the "*"'s was not apparent to me until I
>>>> used the initial example as a starting point and made incremental changes
>>>> until I gotsuccess. So I am not suggesting that RTM should have been
>>>> enough.
>>>
>>> Just remember that plotmath is designed to handle math expressions like
>>> alpha+beta*x and the logic should follow. For the same reason, although it
>>> makes little or no visual difference, you really should say
>>
>> What I did not remember was that there had been prior rhelp questions about
>> how to create a proper prefixed-superscript such as might be use to
>> represent different isotopes of the same element and and solution had been
>> to use a postfixed subscript on a phantom() expression.
>>
>> plot(1,1, xlab=expression(phantom()^32m*K) ) attempted but not successful.
>>
>>> plot(1,1, xlab=expression(phantom()^32*K) )
>>> plot(1,1, xlab=expression(phantom()^32m*K) )
>> Error: unexpected symbol in "plot(1,1, xlab=expression(phantom()^32m"
>>> plot(1,1, xlab=expression(phantom()^"32m"*K) ) # succeeds
>
> I think what PD was trying to say is that a preferred solution would be:
>
> plot(1,1, xlab=expression(phantom()^{32*m}*K) )
I wasn't, so this adds further to my understanding. I had not understood the
need for the use of curley-braces for grouping plotmath expressions from PD's
comment, but do now see the "{items}" construct upon searching on the plotmath
help page.
I suppose you could argue that the framework of :
<symbol> {<open-operator><symbol><close-operator>} {unary-operator} |
{<unary-operator><symbol>}
... might be hinted at by PD's comment, but I was not getting it from the hint.
I guess I'm still too concrete in my thinking, although most of my friends and
acquaintances might say the opposite. I do appreciate all of your help over the
years to fill in the gaps in my knowledge. I have learned a great deal from
each of you.
>
> Peter Ehlers
>
>>
>> There is some sort of parsing that splits the numeric from the alpha
>> characters even with no spaces intervening, so you need to "protect" the 32m
>> with quotes to get error-free interpretation.
>>
>>
>>>
>>> labels=expression(Control, P[2]*O[5], K[2]*S*O[4], Ca*S*O[4])
>>>
>>> (Plotmath as of now doesn't actually do anything about kerning and such,
>>> but TeX afficionados will know that $different$ is quite different from
>>> \textit{different}, the former not being a word but identical to
>>> $dif^2e^2rnt$)
>>>
>>> --
>>> Peter Dalgaard, Professor,
>>> Center for Statistics, Copenhagen Business School
>>>
>>
>>
>> David Winsemius, MD
>> Alameda, CA, USA
>>
>> ______________________________________________
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>> 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
Alameda, CA, USA
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