mfdela · February 13, 2011 00:41 · Feb 13, 2011
diff --git a/tanimoto.rb b/tanimoto.rb
@@ -0,0 +1,22 @@
+#!/usr/bin/ruby
+
+class Array 
+   def sum
+      inject( 0 ) { |sum,x| sum+x }
+   end
+   def sum_square
+      inject( 0 ) { |sum,x| sum+x*x }
+   end
+   def *(other) # dot_product
+      ret = []
+      return nil if !other.is_a? Array || size != other.size
+      self.each_with_index {|x, i| ret << x * other[i]}
+      ret.sum
+   end
+end
+
+def tanimoto(a, b)
+   dot = (a * b)
+   den = a.sum_square + b.sum_square - dot
+   dot.to_f/den.to_f
+end