# lapply returns a list of the same length as X, each element of which
# is the result of applying FUN to the corresponding element of X.
lapply(X, FUN, ...)
sapply(X, FUN, ..., simplify = TRUE, USE.NAMES = TRUE)
vapply(X, FUN, FUN.VALUE, ..., USE.NAMES = TRUE)
replicate(n, expr, simplify = "array")
simplify2array(x, higher = TRUE)