Subsetting lists via logical index vectors

Question

I have a complex list and need to select a subset from it, based on the value of a boolean element (I need records with hidden value e

Answer 1

The example data in the question is a list of length 3 which we shall call L. Each of its components is itself a list and one component of each of these sublists is hidden. We can extract the hidden components of the sublists into a logical vector called hidden. Using that logical vector we can subset the original list L giving a new list containing only those sublists with a hidden component of TRUE.

hidden <- sapply(L, "[[", "hidden") # create logical vector hidden
L[hidden]

For the data provided we get a list with one component:

> length(L[hidden])
[1] 1

and if we knew that there were only one component then L[hidden][[1]] or L[[which(hidden)]] would give that single component.