How to get the nth element of each item of a list, which is itself a vector of unknown length
If we have a list, and each item can have different length. For example: l <- list(c(1, 2), c(3, 4,5), c(5), c(6,7)) (In order to be clear, we will call objects in a list “items”, and objects in the objects of list “elements”.) How can we extract, for example the first element of each item? … Read more