group_by() public

Returns a hash, which keys are evaluated result from the block, and values are arrays of elements in enum corresponding to the key.

If no block is given, an enumerator is returned instead.

(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)