2 files changed, 22 insertions, 1 deletions
diff --git a/lib/nlp_ruby/SparseVector.rb b/lib/nlp_ruby/SparseVector.rb
index 6843b70..fc9d55c 100644
--- a/lib/nlp_ruby/SparseVector.rb
+++ b/lib/nlp_ruby/SparseVector.rb
@@ -1,8 +1,11 @@
 class SparseVector < Hash
 
-  def initialize
+  def initialize arg=nil
     super
     self.default = 0
+    if arg.is_a? Array
+      from_a arg
+    end
   end
 
   def from_a a
@@ -21,6 +24,16 @@ class SparseVector < Hash
     self.values.inject(:+)
   end
 
+  def approx_eql? other, p=10**-10
+    return false if !other
+    return false if other.size!=self.size
+    return false if other.keys.sort!=self.keys.sort
+    self.keys.each { |k|
+      return false if (self[k]-other[k]).abs>p
+    }
+    return true
+  end
+
   def average
     self.sum/self.size.to_f
   end
diff --git a/lib/nlp_ruby/misc.rb b/lib/nlp_ruby/misc.rb
index 1fa3878..80d932c 100644
--- a/lib/nlp_ruby/misc.rb
+++ b/lib/nlp_ruby/misc.rb
@@ -11,6 +11,14 @@ class Array
     }
     return true
   end
+
+  def sum
+    self.inject(:+)
+  end
+
+  def mean
+    self.sum.to_f/self.size
+  end
 end
 
 def spawn_with_timeout cmd, t=4, debug=false