Not sure I understand what you really want, if you have found ways to accomplish what you want but are not satisfied with them. That is one reason why keeping the mailing list involved (by reply-all) is good for you. From my end, I don't do one-on-one support online, and may not be able to carry on a thread to the end if I get busy.

Your concept of a generalized outer function sounds to me like:

myfunc <- function( A, B, C ) {
 A * B + C
}

gouter <- function( FUN, ... ) {
 args <- list( ... )
 DF <- do.call( expand.grid, args )
 array( data = do.call( FUN, DF )
      , dim = sapply( args, FUN=length )
      , dimnames = args
      )
}

gouter( myfunc, A = 1:3, B=2:6, C=3:4 )
# , , C = 3
#
#    B
# A   2  3  4  5  6
#   1 5  6  7  8  9
#   2 7  9 11 13 15
#   3 9 12 15 18 21
#
# , , C = 4
#
#    B
# A    2  3  4  5  6
#   1  6  7  8  9 10
#   2  8 10 12 14 16
#   3 10 13 16 19 22

I generally just tack on columns to the expand.grid result... I almost never have a need for multidimensional arrays.

On Fri, 9 Sep 2016, Steve Kennedy wrote:

Hello,

Abstraction is what I want. I'm actually looking to do something more complicated. The functions do.call, and as.list get me most of the way there, but there is something I'm missing ...

My eventual goal is to produce a multi-dimensional version of 'outer'. Like my.outer(func, a_vec, b_vec, c_vec, ..), where the function of the variables 'a', 'b', 'c', etc. would be applied to the vectors from the outer product of the vectors of values for each variable.

I wanted to use expand.grid (does require reshaping the output). Using temps = c(40,50,60) and times = c(1:5), this doesn't quite seem to work:

  apply(expand.grid(temps,times), 1, function(a) do.call(func2, as.list(a)))

although this does work:

  do.call(func2, as.list(c(10, 121)))

And, this also works:

 apply(expand.grid(temps,times), 1, function(a) do.call("+", as.list(a)))

There is some subtlety here I don't understand.

Thanks,

Steve

-----Original Message-----
From: Jeff Newmiller [mailto:jdnew...@dcn.davis.ca.us]
Sent: Friday, September 09, 2016 5:39 PM
To: Steve Kennedy; r-help@r-project.org
Subject: Re: [R] Apply a multi-variable function to a vector

Your architecture has a bad smell to me. For one thing you are mixing different units in the same vector but should be putting multiple instances of the same variable into one vector. Lists of vectors (data frames) are typically used when multiple variables need to be grouped.

Another problem is that you are constraining the names of the variables you pass to the function to be named the same as they are inside the function. This really limits your use of those functions.

There really is too much abstraction going on here.
--
Sent from my phone. Please excuse my brevity.

On September 9, 2016 12:44:52 PM PDT, Steve Kennedy 
<skenn...@anikatherapeutics.com> wrote:
Hello,

I would like to define an arbitrary function of an arbitrary number of
variables, for example, for 2 variables:

func2 <- function(time, temp) time + temp

I'd like to keep variable names that have a meaning in the problem
(time and temperature above).

If I have a vector of values for these variables, for example in the
2-d case, c(10, 121), I'd like to apply my function (in this case
func2) and obtain the result. Conceptually, something like,

func2(c(10,121))

becomes

func2(10,121)

Is there a simple way to accomplish this, for an arbitrary number of
variables?  I'd like something that would simply work from the
definition of the function.  If that is possible.

Thanks,

Steve Kennedy

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