The [[ operator can be used to extract nested elements of a list by specifying a sequence of indices. For example, the following code would extract the third element of the first element of the list x:
x <- list(a = list(10, 12, 14), b = c(3.14, 2.81))
x[[c(1, 3)]]
This code would first extract the first element of the list x, which is a list. Then, it would extract the third element of the first element of the list x, which is the number 14.
The [[ operator can also be used to extract nested elements of a list by specifying a single index that is a vector of integers. For example, the following code would extract the same element of the list x as the previous code:
x[[1]][[3]]
This code would first extract the first element of the list x, which is a list. Then, it would extract the third element of the first element of the list x, which is the number 14.
The [[ operator can be used to extract nested elements of a list in a variety of ways. The specific syntax that you use will depend on the specific structure of the list that you are trying to subset.
