Create a list from a list without nesting

Question

Lets say I have a list: x <- list(mtcars, iris, cars)

Now lets say I want to add another dataset to the list. Adding one to the end is easy. x[[4]]

Answer 1

You need to have a list to add to the other lists, so:

df <- data.frame(a=1:10)
c(list(df), x)
#List of 4
#...

You can use append too, but you need to pass a list again:

append(list(df),x)
# equivalent to:
append(x, list(df), after=0)

...which means you can specify exactly where you want df added in the order of lists.