[R] sapply problem

[Joerg van den Hoff]

I have encountered the following problem: I need to extract from
a list of lists equally named compenents who happen to be 'one row'
data frames. a trivial example would be:

a <- list(list(
df = data.frame(A = 1, B = 2, C = 3)), list(df = data.frame(A = 4,B = 5,C = 6)))

I want the extracted compenents to fill up a matrix or data frame row by row.
the obvious thing to do seems:

b <- sapply(a, "[[", "df")
b <- t(b)

now `b' looks all right:

b
class(b)

but it turns out that all elements in this matrix are one element lists:

class(b[1,1])

which prevents any further standard processing of `b' (like `colMeans', e.g.)

question 1: is their a straightforward way to enforce that `b' contains
simple numbers as elements right from the start (instead of something like
apply(b, 1:2, "class<-", "numeric") afterwards)?

question 2: should not sapply do this further 'simplification' anyway in a situation
like this (matrix elements turn out to be one-element lists)?

regards

joerg