create all mutant sequences with m mutations or fewer from protein or DNA

kmer_find.rb

class Array
	def expand(master, mut)
		collection = []
		each do |str|
			c = str.count('.') 
			case 
			when c < mut 
				collection << str + master[str.length]
				collection << str + '.'
			when c == mut 

				collection << str + master[str.length]
			end
		end
		collection
	end
	def mutagenize_frags(master, mut, len=master.length)
		var = self.dup
		while var.first.length < len do
			var = var.send(:expand, *[master, mut])
		end
		var.sort
	end
end

class String
	def mutagenize_frags(mut,len=self.length)
		[''].mutagenize_frags(self,mut,len)
	end
end
puts "ABCDEF".mutagenize_frags(5)