Gabor ... that worked perfectly. Thank you. > -----Original Message----- > From: Gabor Grothendieck [mailto:ggrothendi...@gmail.com] > Sent: Monday, August 09, 2010 10:20 PM > To: Derek Ogle > Cc: R (r-help@R-project.org) > Subject: Re: [R] Function to Define a Function > > On Mon, Aug 9, 2010 at 9:31 PM, Derek Ogle <do...@northland.edu> wrote: > > I am trying to define a general R function that has a function as the > output that depends on the user's input arguments (this may make more > sense by looking at the toy example below). My real use for this type > of code is to allow a user to choose from many parameterizations of the > same general model. > > > > My "issue" is that when I compile a package with this type of code in > it I get a __warning__ that "multiple local function definitions for > 'm' with different formal arguments." While this is not a "deadly > error" I would like to avoid the warning if possible. Can someone > provide some guidance? Thank you in advance for any help you can > offer. > > > > For what it is worth ... I am working on a Windows XP machine with R > 2.11.1. > > > > > > > > > > ## A function that allows the user to create a new function that > depends on their > > ## choice in the type argument. As a simple example, if the user > chooses "one" > > ## then the output function is exponential growth, if the user > choses "two" then > > ## thhe output function is logistic growth. > > > > mdlChooser <- function(type=c("one","two")) { > > type <- match.arg(type) > > switch(type, > > one={ m <- function(x,N0,r) N0*exp(x*r) }, > > two={ m <- function(x,N0,r,K) (N0*K)/(N0+(K-N0)*exp(-x*r)) }, > > ) > > m > > } > > > > ## define time steps > > t <- 0:10 > > > > ## create a function -- junk1 -- that produces exponential growth > > junk1 <- mdlChooser("one") > > junk1 > > res1 <- junk1(t,500,0.2) > > res1 > > > > ## create a function -- junk2 -- that produces logistic growth > > junk2 <- mdlChooser("two") > > junk2 > > res2 <- junk2(t,500,0.2,1000) > > res2 > > > > > Try this: > > mdlChooser <- function(type = c("one", "two")) { > one <- function(x,N0,r) N0*exp(x*r) > two <- function(x,N0,r,K) (N0*K)/(N0+(K-N0)*exp(-x*r)) > type <- match.arg(type) > get(type) > }
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