[R] Selecting/Accessing the last vector in a list of a list of data.frames

[Bryan Hanson]

Hello Again R Folks:

I¹m trying to clean up some code.  Suppose I have an object like this:

> str(test)
List of 2
 $ G:List of 2
  ..$ cls:'data.frame':    101 obs. of  2 variables:
  .. ..$ V1: num [1:101] -0.0019 -0.0019 -0.00189 -0.00188 -0.00186 ...
  .. ..$ V2: num [1:101] 0.000206 0.000247 0.000288 0.000329 0.000371 ...
  ..$ rob:'data.frame':    101 obs. of  2 variables:
  .. ..$ V1: num [1:101] -0.00142 -0.00141 -0.0014 -0.00139 -0.00137 ...
  .. ..$ V2: num [1:101] 0.000424 0.000456 0.000487 0.000517 0.000546 ...
 $ T:List of 2
  ..$ cls:'data.frame':    101 obs. of  2 variables:
  .. ..$ V1: num [1:101] -0.00222 -0.00222 -0.00221 -0.00219 -0.00216 ...
  .. ..$ V2: num [1:101] -0.00077 -0.000742 -0.000712 -0.000681 -0.000648
..
  ..$ rob:'data.frame':    101 obs. of  2 variables:
  .. ..$ V1: num [1:101] -0.000981 -0.000979 -0.000972 -0.000961 -0.000946
..
  .. ..$ V2: num [1:101] -0.000332 -0.000303 -0.000274 -0.000245 -0.000216
..

I need to perform some operations on each value of V1 in turn, then each
value of V2 in turn (so for instance I want test$G$cls$V1).  The structure
of this object is nearly constant except the first elements of the list (G,
T in the example) may vary in number and name, so I need something that
accommodates this.

I can do this with loops, but it seems like a job for lapply or rapply, but
these don't quite work.  I've played with quite a few variations, searched
the help archives and found a number of useful ideas, but not quite what I
need.  The only thing that nearly works is do.call(cbind, object) enough
times to bring V1 and V2 "to the surface" but then I've lost my carefully
constructed naming.

Any suggestions appreciated.  It seems like there might be a simple
approach, but I may be too tired right now to see it!

Thanks, Bryan
*************
Bryan Hanson
Professor of Chemistry & Biochemistry
DePauw University, Greencastle IN USA