Ruby - collect same numbers from array into array of arrays

Question

I have created a very ugly script to collect same numbers from an array. I don\'t think this is a very Ruby way :) Anyone could provide a more clean solution?

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Answer 1

Using chunk_while:

[5, 5, 2, 2, 2, 6, 6].chunk_while(&:==).to_a
#=> [[5, 5], [2, 2, 2], [6, 6]]

Ruby prior to 2.3:

[5, 5, 2, 2, 2, 6, 6].each_with_object([]) do |e, acc|
  acc.last && acc.last.last == e ? acc.last << e : acc << [e]
end
#=> [[5, 5], [2, 2, 2], [6, 6]]

Answer 2

In case if you want to do it without order:

ar.group_by(&:itself).values
 => [[5, 5], [2, 2, 2], [6, 6]]

Answer 3

[5, 5, 2, 2, 2, 6, 6].slice_when(&:!=).to_a
  #=> [[5, 5], [2, 2, 2], [6, 6]] 

One could perhaps say that Enumerable#chunk_while and Enumerable#slice_when are ying and yang.

Prior to Ruby v2.3, one might write

[5, 5, 2, 2, 2, 6, 6].chunk(&:itself).map(&:last)

and prior to v2.2,

[5, 5, 2, 2, 2, 6, 6].chunk { |n| n }.map(&:last)

Answer 4

just another oneliner

arr = [5, 5, 2, 2, 2, 6, 6] 
arr.uniq.map {|e| [e]*arr.count(e) }
# => [[5, 5], [2, 2, 2], [6, 6]]