R help - Jun 2013 - plyr _aply simplifying return-value dimensions

hi all -- let's say i have the following simplified plyr code:
> factor_table <- data.frame(dim1 = 1:10, dim2 = 1:4)
> foo <- maply(factor_table, function(dim1, dim2) list(a =
"foo", b runif(10)))
foo will now be a 10 x 4 x 2 array (of mode 'list'), and i'll have
to
access a "b" element like so:
> foo[[1,1,"b"]]
if i replace the anonymous function with another that returns a
variable-length list, however, foo will be a 10 x 4 array (again of mode
'list'), and i'll have to access a "b" element like
so:
> foo[[1,1]]$b  ## or foo[[1,1]][["b"]]
i tend to prefer this latter approach, since it's agnostic to the called
function in the maply loop, and thus makes downstream coding more
consistent (in case upstream functions change, the addressing scheme
required to recover that function's various return values is somewhat
uniform).

does anyone know if we can "force" plyr to _not_ try to simplify along
the
inner function's return value length when using the _aply family of calls?

cheers,

-m

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Will using the function mlply() rather than maply() do the trick for you?

For example
dat <- data.frame(dim1=1:10, dim2=1:10)
foo <- maply(dat, function(dim1, dim2) list(a="foo", b=runif(10)))
foo2 <- mlply(dat, function(dim1, dim2) list(a="foo", b=runif(10)))

Jean


On Wed, Jun 5, 2013 at 12:33 AM, Murat Tasan <mmuurr@gmail.com> wrote:
> hi all -- let's say i have the following simplified plyr code:
>
> > factor_table <- data.frame(dim1 = 1:10, dim2 = 1:4)
> > foo <- maply(factor_table, function(dim1, dim2) list(a =
"foo", b > runif(10)))
>
> foo will now be a 10 x 4 x 2 array (of mode 'list'), and i'll
have to
> access a "b" element like so:
> > foo[[1,1,"b"]]
>
> if i replace the anonymous function with another that returns a
> variable-length list, however, foo will be a 10 x 4 array (again of mode
> 'list'), and i'll have to access a "b" element like
so:
> > foo[[1,1]]$b  ## or foo[[1,1]][["b"]]
>
> i tend to prefer this latter approach, since it's agnostic to the
called
> function in the maply loop, and thus makes downstream coding more
> consistent (in case upstream functions change, the addressing scheme
> required to recover that function's various return values is somewhat
> uniform).
>
> does anyone know if we can "force" plyr to _not_ try to simplify
along the
> inner function's return value length when using the _aply family of
calls?
>
> cheers,
>
> -m
>
>         [[alternative HTML version deleted]]
>
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