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_schwa...@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.4...@gmail.com> wrote:
Yes, plot(z,y,..)
Bert
On Thu, Jun 6, 2019 at 9:21 AM Nick Wray <nicholas.w...@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.4...@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@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_schwa...@me.com> wrote:
On Jun 6, 2019, at 11:19 AM, Nick Wray via R-help <
r-help@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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