[R] pass functions and arguments to function

[Hao Cen]

Thanks. I don't know how many functions there will be.

What if g1, g2, g3 have variable number of parameters? say g1 has parg1a,
parg1b, and g3 has parg3a, parg3b, parg3c, parg4d.

 f <- function(X, fs, pars) {
    process1(X)
    for (i in 1:length(fs))
      fs[[i]](pars[[i]])   # doesn't work here

    process2(X)

 }


On Tue, December 29, 2009 4:57 pm, Duncan Murdoch wrote:
> On 29/12/2009 3:08 PM, Hao Cen wrote:
>
>> Hi,
>>
>>
>> I wonder how to pass several functions and their arguments as arguments
>> to a function. For example, the main function is
>>
>> f = function(X  ) { process1(X) ...
>>
>>
>>
>> process2(X) }
>>
>>
>> I have a few functions that operate on X, e.g. g1(X, par1), g2(X,
>> par2), g3(X, par3).  par1, par2 and par3 are parameters and of different
>> types. I would like to pass g1, g2, g3 and their arguments to f and g1,
>> g2, g3 may appear to be in different orders. So that final effect of the
>> passing is
>
> Just pass them.  If you know there are three functions, set up f as
>
>
> f <- function(X, f1, f2, f3, par1, par2, par3) { process1(X) f1(X, par1)
> f2(X, par2) f3(X, par3) process2(X) }
>
>
> and call it as
>
> f(X, g1, g2, g3, par1, par2, par3)
>
> If you don't know how many functions there will be, put them in a list:
>
>
> f <- function(X, fs, pars) { process1(X) for (i in 1:length(fs))
> fs[[i]](pars[[i]]) process2(X) }
>
>
> and call it as
>
> f(X, list(g1, g2, g3), list(par1, par2, par3))
>
> Duncan Murdoch
>
>
>>
>> f = function(X  ) { process1(X) g1(X, par1) g2(X, par2) g3(X, par3)
>> process2(X) }
>>
>>
>> If I pass g2(X, par2),g3(X, par3), g1(X, par1) to f, I would expect to
>> get the effect of f = function(X  ) { process1(X) g2(X, par2) g3(X, par3)
>> g1(X, par1) process2(X) }
>>
>>
>> Appreciate any suggestions.
>>
>>
>> thanks
>>
>> Jeff
>>
>>
>>
>> ps please ignore my previous blank subject email. It was accidentally
>> sent before the letter was completed.
>>
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>
>
>