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

[Alberto Monteiro]

Ted Harding asked:
>
> 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)
> 
Hmmmm...

Did you try this?

# reproducible example
C.W <- list(list(level = 1, x = 2), list(level = 2, y = 3), list(level = 10, 
z = 4))
sapply(C.W, function(x) x$level)

Alberto Monteiro