mjtko/set_subset_ext.rb

Created May 4, 2012 20:29

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Subset for a set

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set_subset_ext.rb

	require 'set'

	class Set
	def subset(&pred)
	Set.new.tap do \|subset\|
	each do \|x\|
	subset << x if pred.call(x)
	end
	end
	end
	end

Author

mjtko commented May 4, 2012

eg.

irb(main):003:0> set = Set[*1..50]
=> #<Set: {49, 38, 27, 16, 5, 44, 33, 22, 11, 50, 39, 28, 17, 6, 45, 34, 23, 12, 1, 40, 29, 18, 7, 46, 35, 24, 13, 2, 41, 30, 19, 8, 47, 36, 25, 14, 3, 42, 31, 20, 9, 48, 37, 26, 15, 4, 43, 32, 21, 10}>
irb(main):004:0> set.subset { |x| x % 7 == 0 }
=> #<Set: {49, 28, 7, 35, 14, 42, 21}>

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