[R] Pasting R code lines into labels

[Marc Schwartz]

Hi,

Sorry for the misfire on the first attempt.

After seeing the clarifications, I thought about a possible way to do this, perhaps a little more simply, while encapsulating the plotting in a function:

plotFx <- function(x, fun) {
  plot(x, fun(x), main = paste0("Plot of y = ", deparse(fun)[2]))
}

So let's say that you have:

x <- 1:10

f <- function(x) x^2
plotFx(x, f)

f <- function(x) cos(x)
plotFx(x, f)

f <- function(x) exp(x) + 1
plotFx(x, f)


In the case of the first function, you get:

> deparse(f)
[1] "function (x) " "x^2" 

for the second:

> deparse(f)
[1] "function (x) " "cos(x)" 

and for the third:

> deparse(f)
[1] "function (x) " "exp(x) + 1" 


Thus, the "deparse(fun)[2]" snippet within the internal paste0() function call, gets you the second, textual part of the function body, which can then be passed as a character vector to the titles or other labels as needed.

A potential gotcha that I would envision, is that the default width in the character vector resulting from deparse() is 60. Thus, by default the function body would broken up into multiple character segments, no longer than approximately 60 characters each. Thus, if you envision that you might end up with very long formulae on x, you may need to adjust the width.cutoff argument in the deparse() call, and likely need to do some additional formatting of the labels in the plot as apropos.

There may be other functional nuances that I am missing here, but this may be a suitable approach.

Regards,

Marc


> On Jun 6, 2019, at 2:11 PM, Bert Gunter <bgunter.4567 using gmail.com> wrote:
> 
> Yes, plot(z,y,..)
> 
> Bert
> 
> On Thu, Jun 6, 2019 at 9:21 AM Nick Wray <nicholas.wray using ntlworld.com> wrote:
> 
>> Thanks Bert, that is exactly what I wanted.  I think that you meant
>> plot(z,y... in the last line?
>> 
>> Nick
>> 
>> On 06 June 2019 at 17:13 Bert Gunter <bgunter.4567 using gmail.com> wrote:
>> 
>> ... and if you wanted too streamline the process, something like the
>> following could be encapsulated in a function:
>> 
>> fun <- quote(exp(x))
>> z <- 1:9
>> y <- eval(fun,list(x = z) )
>> plot(x, y, main = paste("Plot of y =", deparse(fun)))
>> 
>> Further details can be found in the "Computing on the Language" section of
>> the "R Language Reference" manual or from suitable tutorials on the web.
>> 
>> Bert Gunter
>> 
>> "The trouble with having an open mind is that people keep coming along and
>> sticking things into it."
>> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
>> 
>> 
>> On Thu, Jun 6, 2019 at 8:55 AM Nick Wray via R-help < r-help using r-project.org>
>> wrote:
>> 
>> Thanks but that's not quite what I meant
>> I am trying out different functions and they don't necessarily vary in a
>> regular way (like say all being powers of x where it'd be simple to just
>> have a vector for the powers you want)
>> So I might have
>> y<-x^2
>> y<-cos(x)
>> y<-exp(x+1)
>> What I am after is a way of running these functions and then calling each
>> one into the labelling for the appropriate graph as I plot it.  So then I
>> would have something like
>> mainlab<-paste("Plot of ",function in question)
>> ...? Thanks Nick
>> 
>>> On 06 June 2019 at 16:40 Marc Schwartz < marc_schwartz using me.com> wrote:
>>> 
>>> 
>>> 
>>>> On Jun 6, 2019, at 11:19 AM, Nick Wray via R-help <
>> r-help using r-project.org> wrote:
>>>> 
>>>> Is there any way of taking a line of r code (eg y<-x^2) and pasting
>> that line of code, as is, into a label, so that for example I could then
>> have a plot label "Plot of y<-x^2"?
>>>> 
>>>> Thanks Nick Wray
>>> 
>>> 
>>> Hi,
>>> 
>>> See ?plotmath
>>> 
>>> An example:
>>> 
>>> x <- 1:10
>>> y <- x^2
>>> 
>>> plot(x, y, main = expression(paste("Plot of ", y %<-% x^2)))
>>> 
>>> 
>>> There are other incantations and examples on the help page above.
>>> 
>>> Regards,
>>> 
>>> Marc Schwartz
>>>