How to get array from string contained identical symbols in Ruby?

I have string like this: "1112222355". How can I get array like that ["111","2222","3","55"] using Ruby?

Assuming you want to group only consecutive elements, use Enumerable#chunk:

> "1112222355".chars.chunk { |x| x }.map { |c, cs| cs.join }=> ["111", "2222", "3", "55"]

"1112222355".scan(/((.)\2*)/).map(&:first)# => ["111", "2222", "3", "55"]