Patrick Burns wrote:
Duncan Murdoch wrote:
On 3/19/2009 12:49 PM, Edna Bell wrote:
Dear R Gurus:
I read somewhere that functions are considered vectors.
Is this true, please?
Your question is a little ambiguous (you probably did read that, and
probably someone does consider them to be vectors), but I think the
right answer is no: when the R documentation talks about vectors, it
is not talking about functions, and the is.vector() function returns
FALSE for functions.
Duncan Murdoch
It could be that you read that about S+ functions,
where they can be thought of as (very special)
vectors. R functions are different in this respect.
Yes. Not that different though. You can't do e.g. mean[[1]] as you can in S:
> mean[[1]]
Error in mean[[1]] : object of type 'closure' is not subsettable
However, also in R, functions can be converted to and from generic
vectors (i.e., lists) using as.list/as.function. The last element in the
list form is the function body, the others are the default argument list.
> mn <- as.list(mean)
> names(mn)[1]<-"foo"
> as.function(mn)
function (foo, ...)
UseMethod("mean")
> mn
$foo
$...
[[3]]
UseMethod("mean")
(Notice that this is mainly a mechanism to allow porting of sneaky S
codes. In R, you'd more likely do it with formals() and body() and their
assignment forms.)
--
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