group_by() public

Groups the collection by result of the block. Returns a hash where the keys are the evaluated result from the block and the values are arrays of elements in the collection that correspond to the key.

If no block is given an enumerator is returned.

(1..6).group_by { |i| i%3 }   #=> {0=>[3, 6], 1=>[1, 4], 2=>[2, 5]}
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February 12, 2016
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group on hash

‘

def group_by_hash hash, value
  hash.group_by do |k,v| 
    v > value ? "Big" : "Small"
  end
end

marks = {"Chair" => 30, "Table" => 40, "Bed" => 60, "stool" => 20}
group_by_hash(marks, 30)