[R] Simple extraction of level,x,y from contourLines()

[(Ted Harding)]

A follow-up to my previous query.

Say one of the results returned by contourLines() is

  C.W <- contourLines(....)

Then C.W is a list of (in this case 28) lists,
each of which is a list with components $level (a single number),
$x (the x coords of the points on a contour at that level) and
$y (the y coords).

I can of course get these individually with, for the 5th one for
instance,

  C.W[[5]]$level
  C.W[[5]]$x
  C.W[[5]]$y

But I can't see how to obtain, in one line and without running
a nasty loop, to get all the levels at once!

In other words, I'm looking for an expression which will return
the vector

  c(C.W[[1]]$level,C.W[[2]]$level,...,C.W[[28]]$level)

(This is probably something I should already have learned from
the documentation, but I think I may have been asleep during
that class ... ).

With thanks,
Ted.

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E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
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Date: 22-Oct-09                                       Time: 19:57:09
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