From b6820b015c1a2767916e3d894cd9cd76d67b94b9 Mon Sep 17 00:00:00 2001
From: Patrick Simianer <p@simianer.de>
Date: Thu, 16 Jul 2015 15:51:20 +0200
Subject: SparseVector: norm, unit

---
 lib/zipf/SparseVector.rb | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'lib')

diff --git a/lib/zipf/SparseVector.rb b/lib/zipf/SparseVector.rb
index 5d219b8..976ecaf 100644
--- a/lib/zipf/SparseVector.rb
+++ b/lib/zipf/SparseVector.rb
@@ -199,5 +199,20 @@ class SparseVector < Hash
     mean.each_pair { |k,v| mean[k] = v/n }
     return mean
   end
+
+  def norm
+    return Math.sqrt(self.dot(self))
+  end
+
+  def unit!
+    n = self.norm
+    self.each_pair { |k,v|
+      self[k] /= n
+    }
+  end
+
+  def unit
+    return SparseVector.new(self).unit!
+  end
 end
 
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