On 07/08/2014 07:21, Joshua Wiley wrote:
Hi Ryan,
It does work, but the *apply family of functions always pass to the first
argument, so you can specify e2 = , but not e1 =. For example:
sapply(1:3, `>`, e2 = 2)
[1] FALSE FALSE TRUE
That is not true:
gt <- function(x, y) x > y
> sapply(1:3, gt, y=2)
[1] FALSE FALSE TRUE
> sapply(1:3, gt, x=2)
[1] TRUE FALSE FALSE
Specifying the first argument(s) in an apply
call is a standard way of getting flexibility.
I'd hazard to guess that the reason the original
version doesn't work is because `>` is Primitive.
There's speed at the expense of not behaving quite
the same as typical functions.
Pat
From ?sapply
'lapply' returns a list of the same length as 'X', each element of
which is the result of applying 'FUN' to the corresponding element
of 'X'.
so `>` is applied to each element of 1:3
`>`(1, ...)
`>`(2, ...)
`>`(3, ...)
and if e2 is specified than that is passed
`>`(1, 2)
`>`(2, 2)
`>`(3, 2)
Further, see ?Ops
If the members of this group are called as functions, any
argument names are removed to ensure that positional matching
is always used.
and you can see this at work:
`>`(e1 = 1, e2 = 2)
[1] FALSE
`>`(e2 = 1, e1 = 2)
[1] FALSE
If you want to the flexibility to specify which argument the elements of X
should be *applied to, use a wrapper:
sapply(1:3, function(x) `>`(x, 2))
[1] FALSE FALSE TRUE
sapply(1:3, function(x) `>`(2, x))
[1] TRUE FALSE FALSE
HTH,
Josh
On Thu, Aug 7, 2014 at 2:20 PM, Ryan <rec...@bwh.harvard.edu> wrote:
Hi,
I'm wondering why calling ">" with named arguments doesn't work as
expected:
args(">")
function (e1, e2)
NULL
sapply(c(1,2,3), `>`, e2=0)
[1] TRUE TRUE TRUE
sapply(c(1,2,3), `>`, e1=0)
[1] TRUE TRUE TRUE
Shouldn't the latter be FALSE?
Thanks for any help,
Ryan
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