R help - Jan 2015 - How to use curve() function without using x as the variable name inside expression?

Hi Bill,

You solved by problem.  For some reason, I thought xname was only referring
to name of the x-axis.

I remember last time I fixed it, it was something about xname, couldn't get
it right this time.

Thanks!  Saved me hours from frustration.

Mike

On Thu, Jan 29, 2015 at 9:04 PM, William Dunlap <wdunlap at tibco.com>
wrote:
> Does
>    help(curve)
> talk about its 'xname' argument?
>
> Try
>    curve(10*foofoo, from=0, to=17, xname="foofoo")
>
> You will have to modify your function, since curve() will
> call it once with a long vector for the independent variable
> and func(rnorm(10), rnorm(10), mu=seq(0,5,len=501)) won't
> work right.
>
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
> On Thu, Jan 29, 2015 at 5:43 PM, C W <tmrsg11 at gmail.com> wrote:
>
>> Hi Rui,
>>
>> Thank you for your help.  That works for now, but eventually, I need to
be
>> pass in x and y.
>>
>> Is there a way to tell the curve() function, x is a fix vector, mu is a
>> variable!
>>
>> Thanks,
>>
>> Mike
>>
>> On Thu, Jan 29, 2015 at 5:25 PM, Rui Barradas <ruipbarradas at
sapo.pt>
>> wrote:
>>
>> > Hello,
>> >
>> > The following will work, but I don't know if it's what you
want. func2
>> > will get x and y from the global environment.
>> >
>> > func2 <- function(mu){
>> >    x + y + mu ^ 2
>> > }
>> >
>> > curve(func2, from = 0, to = 10)
>> >
>> >
>> > Hope this helps,
>> >
>> > Rui Barradas
>> >
>> > Em 29-01-2015 21:02, C W escreveu:
>> >
>> >> Hi all,
>> >>
>> >> I want to graph a curve as a function of mu, not x.
>> >>
>> >> Here's the R code:
>> >>
>> >> x <- rnorm(10)
>> >> y <- rnorm(10)
>> >>
>> >> func <- function(x, y, mu){
>> >>     x + y + mu ^ 2
>> >> }
>> >>
>> >> curve(f = func(x = x, y = y, mu), from = 0, to = 10)
>> >> I know I can change variable mu to x, but is there a way to
tell R
>> that mu
>> >> is the variable of interest, not x.
>> >>
>> >> Thanks in advance,
>> >>
>> >> Mike
>> >>
>> >>         [[alternative HTML version deleted]]
>> >>
>> >> ______________________________________________
>> >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and
more, see
>> >> 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.
>> >>
>> >>
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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.
>>
>
>
	[[alternative HTML version deleted]]

Hi Bill,

One quick question.  What if I wanted to use curve() for a uniform
distribution?

Say, unif(0.5, 1.3), 0 elsewhere.

My R code:
func <- function(min, max){
  1 / (max - min)
}

curve(func(min = 0.5, max = 1.3), from = 0, to = 2)

curve() wants an expression, but I have a constant.   And I want zero
everywhere else.

Thanks,

Mike

On Thu, Jan 29, 2015 at 10:34 PM, C W <tmrsg11 at gmail.com> wrote:
> Hi Bill,
>
> You solved by problem.  For some reason, I thought xname was only
> referring to name of the x-axis.
>
> I remember last time I fixed it, it was something about xname, couldn't
> get it right this time.
>
> Thanks!  Saved me hours from frustration.
>
> Mike
>
> On Thu, Jan 29, 2015 at 9:04 PM, William Dunlap <wdunlap at
tibco.com> wrote:
>
>> Does
>>    help(curve)
>> talk about its 'xname' argument?
>>
>> Try
>>    curve(10*foofoo, from=0, to=17, xname="foofoo")
>>
>> You will have to modify your function, since curve() will
>> call it once with a long vector for the independent variable
>> and func(rnorm(10), rnorm(10), mu=seq(0,5,len=501)) won't
>> work right.
>>
>>
>> Bill Dunlap
>> TIBCO Software
>> wdunlap tibco.com
>>
>> On Thu, Jan 29, 2015 at 5:43 PM, C W <tmrsg11 at gmail.com>
wrote:
>>
>>> Hi Rui,
>>>
>>> Thank you for your help.  That works for now, but eventually, I
need to
>>> be
>>> pass in x and y.
>>>
>>> Is there a way to tell the curve() function, x is a fix vector, mu
is a
>>> variable!
>>>
>>> Thanks,
>>>
>>> Mike
>>>
>>> On Thu, Jan 29, 2015 at 5:25 PM, Rui Barradas <ruipbarradas at
sapo.pt>
>>> wrote:
>>>
>>> > Hello,
>>> >
>>> > The following will work, but I don't know if it's what
you want. func2
>>> > will get x and y from the global environment.
>>> >
>>> > func2 <- function(mu){
>>> >    x + y + mu ^ 2
>>> > }
>>> >
>>> > curve(func2, from = 0, to = 10)
>>> >
>>> >
>>> > Hope this helps,
>>> >
>>> > Rui Barradas
>>> >
>>> > Em 29-01-2015 21:02, C W escreveu:
>>> >
>>> >> Hi all,
>>> >>
>>> >> I want to graph a curve as a function of mu, not x.
>>> >>
>>> >> Here's the R code:
>>> >>
>>> >> x <- rnorm(10)
>>> >> y <- rnorm(10)
>>> >>
>>> >> func <- function(x, y, mu){
>>> >>     x + y + mu ^ 2
>>> >> }
>>> >>
>>> >> curve(f = func(x = x, y = y, mu), from = 0, to = 10)
>>> >> I know I can change variable mu to x, but is there a way
to tell R
>>> that mu
>>> >> is the variable of interest, not x.
>>> >>
>>> >> Thanks in advance,
>>> >>
>>> >> Mike
>>> >>
>>> >>         [[alternative HTML version deleted]]
>>> >>
>>> >> ______________________________________________
>>> >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and
more, see
>>> >> 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.
>>> >>
>>> >>
>>>
>>>         [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more,
see
>>> 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.
>>>
>>
>>
>
	[[alternative HTML version deleted]]

On 31/01/15 21:10, C W wrote:
> Hi Bill,
>
> One quick question.  What if I wanted to use curve() for a uniform
> distribution?
>
> Say, unif(0.5, 1.3), 0 elsewhere.
>
> My R code:
> func <- function(min, max){
>    1 / (max - min)
> }
>
> curve(func(min = 0.5, max = 1.3), from = 0, to = 2)
>
> curve() wants an expression, but I have a constant.   And I want zero
> everywhere else.
Well if that's what you want, then say so!!!

func <- function(x,min,max) {
    ifelse(x < min | x > max, 0, 1/(max - min))
}

curve(func(u,0.5,1.3),0,2,xname="u")

Or, better (?) curve(func(u,0.5,1.3),0,2,xname="u",type="s")

which avoids the slight slope in the "vertical" lines.

cheers,

Rolf Turner

-- 
Rolf Turner
Technical Editor ANZJS
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276
Home phone: +64-9-480-4619