rubyで部分集合と上位集合を確認する方法
class Array def subset?(other) return (self - other).empty? end def superset?(other) return other.subset?(self) end end a = [1,2,3,4] b = [2,3] c = [2,3,4,5] puts c.subset? a #false puts b.subset? a #true puts c.superset? b #false
※The Ruby Wayの方法を修正(第二版P220)