How to predefine the length of a list

Question

How can I create a list of size n? For example, lines = read.table(filename, sep="\n") how would I create a list called linesCopy that is of the size of lines?

I tried something like linesCopy <- [[length(lines)]] but this throws unexpected token [[

Answer 1

A list is just a vector, you can create a list of any size using vector().

For example, a list of size 4:

vector("list", 4)
[[1]]
NULL

[[2]]
NULL

[[3]]
NULL

[[4]]
NULL

Or, specific in your case, a list named linesCopy with the same size as the length of lines:

linesCopy <- vector("list", length(lines))