[R] Pasting R code lines into labels

[Duncan Murdoch]

These look like very fragile suggestions.  Allow x^2 to be an argument 
(named expr, for example) to plotFx, don't force a user to write a 
function in a very particular way.  Then use deparse(substitute(expr)) 
in the title.

Duncan Murdoch

On 06/06/2019 4:33 p.m., Bert Gunter wrote:
> Well, if you want to do it this way, note that as written, the y axis
> default label isn't "nice," and you should anyway allow for additional
> graphical arguments (either way). Also, slightly better I think is to use
> the built-in access function, body():
> 
> plotFx <- function(x, fun, ...) {
>     plot(x, fun(x), main = paste0("Plot of y = ", deparse(body(fun))), ...)
> }
> x <- 1:10
> f <- function(x) x^2
> plotFx(x, f, col = "red", ylab = "y")
> 
> 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 12:19 PM Marc Schwartz <marc_schwartz using me.com> wrote:
> 
>> 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
>>>>>
>>
>>
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