Selecting single elem. with [[ and $

Extracting a single element with [[ or $ returns the element, not a subset of the input object.

Hence the element is always the simplest representation.
For a vector, this is a scalar (vector of length 1).

• [[: takes a position or a name (e.g. x[[1]] or x[["apple"]])
• $: only takes a name (e.g. x$apple)
  • equivalent is dplyr::pull()