Ruby: undefined method 'to_set' for array?
Problem Description:
I have a large array of chars:
input = ["p", "f", "p", "t" ... "g"]
I am attempting to take a slice of the array and convert it into a set:
sub = input.slice(0, 4).to_set
But the interpreter bombs:
undefined method `to_set' for ["p", "f", "p", "t"]:Array (NoMethodError)
Why is this happening? In irb this code executes with no issues.
Solution – 1
The Enumerable#to_set method is implemented by Ruby’s Set. It is not require-d by default hence why you get the error if you try to use it.
But in irb Set is already required. You can verify that by:
require 'set' # => false
This is something that has been raised up as an issue in irb before.