8 lines
		
	
	
		
			160 B
		
	
	
	
		
			Ruby
		
	
	
	
	
	
		
		
			
		
	
	
			8 lines
		
	
	
		
			160 B
		
	
	
	
		
			Ruby
		
	
	
	
	
	
|   | module Enumerable | ||
|  |   def group_by | ||
|  |     inject({}) do |h, e| | ||
|  |       h.fetch(yield(e)) { |k| h[k] = [] } << e; h | ||
|  |     end | ||
|  |   end unless method_defined?(:group_by) | ||
|  | end |