R help - May 2012 - Creating functions with a loop.

Hi

I am trying to create n functions where each function is defined in function one
step before, i.e. something like

ff.k(x) = ff.j(x) - sum(1:j),      for j=k-1

Is it possible? If it isn't and I manually create each function then is
their a way to call them through a loop?  My objective is to calculate something
like

result.k = ff.k(x1)/ff.k(x2)      for k in 2:n

Thank you for your time,
Etienne

On May 22, 2012, at 10:06 AM, Etienne Larriv?e-Hardy wrote:
> Hi
>
> I am trying to create n functions where each function is defined in  
> function one step before, i.e. something like
>
> ff.k(x) = ff.j(x) - sum(1:j),      for j=k-1
There is a cumsum function:

 > cumsum(1:10)
  [1]  1  3  6 10 15 21 28 36 45 55

Did you mean something like?:

  ff.k[j] <- ff.j[j] - sum(1:j),      for j=k-1

In R the paren, "(", indicates that you are calling a function whereas
you appear interested in making an indexed assignment to a vector.
>
> Is it possible? If it isn't and I manually create each function then  
> is their a way to call them through a loop?  My objective is to  
> calculate something like
>
> result.k = ff.k(x1)/ff.k(x2)      for k in 2:n
You may have clear idea about which k-indices should go where in that  
expression, but I surely do not. What are 'x1' and 'x2'?

-- 

David Winsemius, MD
West Hartford, CT

Hello,

To keep related objects of the same nature in the same structure makes 
very good sense but why not name the functions in the list after they 
were created?

Using 'NextFunc' of a previous post,


f.list <- list()
f.list[[1]] <- function(x) x^2
f.list[[2]] <- NextFunc(f, 1)
f.list[[3]] <- NextFunc(f2, 2)

names(f.list) <- paste("ff", 1:3, sep=".")

f.list[[ 3 ]](3) # 6 = 3^2 - 1 - 2
f.list[[ "ff.3" ]](3) # the same
f.list$ff.3(3) # the same


Hope this helps,

Rui Barradas
Em 23-05-2012 11:00, "R. Michael Weylandt" <michael.weylandt at
gmail.com>
escreveu:
> Date: Tue, 22 May 2012 18:50:08 -0400
> From: "R. Michael Weylandt"<michael.weylandt at gmail.com>
> To: Etienne Larriv?e-Hardy 	<etienne.larrivee-hardy.1 at ulaval.ca>
> Cc:r-help at r-project.org
> Subject: Re: [R] Creating functions with a loop.
> Message-ID:
> 	<CAAmySGMpyobjLP5qHRg3S6UM0C5T08Yn-CUiUg9eQ2SSTobLpw at
mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> You can do what you want with the get() and assign() functions, though
> it might be easier and better to use match.fun() than get()
>
> Much better though would be to build your functions in a list and call
> the n-th element of the list with syntax like
>
> f.list[[3]](4)
>
> will call the function in the third element of the list with argument 4.
>
> Best,
> Michael
>
> On Tue, May 22, 2012 at 1:24 PM, Etienne Larriv?e-Hardy
> <etienne.larrivee-hardy.1 at ulaval.ca>  wrote:
>> >  Michael's method seems to be working but I still can't
get to wrap it in a
>> >  loop since I cannot get the loop to dynamically change the
functions' name,
>> >  i.e. ff1, ff2, ff3, ... In other words, I would need the first
iteration to
>> >  create the function ff1, the second to create the function ff2,
...
>> >  Furthermore, does anyone know of a way to call said functions
from a loop in
>> >  a way that the first step of the loop calls ff1, the second calls
ff2 and so
>> >  on?
>> >
>> >  The 2 problems should be closely related I think.
>> >
>> >  Thanks for the time
>> >
>> >  --
>> >  View this message in
context:http://r.789695.n4.nabble.com/Creating-functions-with-a-loop-tp4630896p4630938.html
>> >  Sent from the R help mailing list archive at Nabble.com.
>> >