probability.rb in facets-1.0.0

- old
+ new
@@ -1,58 +1,116 @@
-require 'nano/enumerable/probability.rb'
\ No newline at end of file
+#--
+# Credit goes to Brian Schröder for current code
+# and Derek for original.
+#++
+module Enumerable
+
+  # Generates a hash mapping each unique symbol in the array
+  # to the relative frequency, i.e. the probablity, of
+  # it appearence.
+  def probability
+    probs = Hash.new(0.0)
+    size = 0.0
+    each do | e |
+      probs[e] += 1.0
+      size += 1.0
+    end
+    probs.keys.each { |e| probs[e] /= size }
+    probs
+  end
+
+# old def
+#
+#   def probability
+#     arr = self.to_a
+#     probHash = Hash.new
+#     size = arr.size.to_f
+#     arr.uniq.each do |i|
+#       ct = arr.inject(0) do |mem,obj|
+#         obj.eql?(i) ? (mem+1) : mem
+#       end
+#       probHash[i] = ct.to_f/size
+#     end
+#     probHash
+#   end
+
+end
+
+
+
+#  _____         _
+# |_   _|__  ___| |_
+#   | |/ _ \/ __| __|
+#   | |  __/\__ \ |_
+#   |_|\___||___/\__|
+#
+=begin test
+
+  require 'test/unit'
+
+  class TCEnumerable < Test::Unit::TestCase
+
+    def test_probability
+      assert_equal( {'a'=>0.5,'b'=>0.5}, %w{a b}.probability )
+      assert_equal( {'tom'=>0.5,'boy'=>0.5}, %w{tom boy}.probability )
+    end
+
+  end
+
+=end